The latest developments on the situation in Libya, where coalition forces launched a series of coordinated airstrikes on Saturday after they were convinced Libyan leader Moammar Gadhafi was not adhering to a cease-fire mandated by the United Nations. Read our complete story and check out our full coverage on unrest in the Arab world. Also, don't miss a gripping, high-resolution gallery of images from Libya.

[11 p.m. Monday ET, 5 a.m. Tuesday in Libya] The United States fired 20 Tomahawk cruise missiles into Libya in the past 12 hours, a military spokeswoman said early Tuesday morning from the Mediterranean Sea. A total of 159 Tomahawks have been fired by the United States and the United Kingdom since an international coalition started Operation Odyssey Dawn on Saturday.

Cmdr. Monica Rousselow, a spokeswoman for the task force, also said one of the three U.S. submarines that participated at the beginning of the operation has since departed the area. She declined to say which submarine.

[8:59 p.m. Monday ET, 2:59 a.m. Tuesday in Libya] In a rare public spat, Russian President Dmitry Medvedev criticized his political mentor, Prime Minister Vladimir Putin, for Putin's comments over the use of force against Libya.

Putin on Monday said the U.N. Security Council resolution authorizing a no-fly zone over Libya was "obviously incomplete and flawed." He added that it "resembles a medieval appeal for a crusade in which somebody calls upon somebody to go to a certain place and liberate it."

A few hours later Medvedev weighed in, scolding Putin's comments, without using the prime minister's name. "It is absolutely inexcusable to use expressions that, in effect, lead to a clash of civilizations - such as 'crusades,' and so on. That is unacceptable," Medvedev said.

[8:10 p.m. Monday ET, 2:10 a.m. Tuesday in Libya] CNN correspondent Nic Robertson has rejected a Fox News report that he and other journalists were used as human shields by the Libyan government to prevent a missile attack on Gadhafi's compound.

Libyan government officials brought CNN and other news crews to the compound to view a building that was damaged late Sunday in a coalition air strike. The Fox story, posted on the outlet's website Monday, says the journalists' presence forced a British aircraft to call off firing seven missiles at the area that already had been hit.

Robertson, who was part of the CNN crew cited in the Fox story, called the rival network's report "outrageous and hypocritical." Robertson said a Fox staffer was among the journalists on the trip - which was not mentioned in the Fox report - and that the journalists in the group were hurried through their trip by their minders.

"If they wanted to use us as human shields ... they would have kept us there longer," Robertson said. "That's not what happened."

[7:49 p.m. Monday ET, 1:49 a.m. Tuesday in Libya] More U.S. legislators are expressing concern about the country's involvement in the coalition military operation in Libya. Delegate Eleanor Holmes Norton, D-District of Columbia, says the president is "stirring up a lot of controversy."

"We're not coordinating with the rebels. Are we going to leave them surrounded, and with the mercy of Gadhafi? I've never seen anything so confused in my life," Norton told CNN.

On the right, lawmakers are demanding the president better explain the U.S. mission in Libya to Congress and the American people, CNN's Dana Bash reports.

"The president should come home and call the Congress back into session and to make his case. He needs to define what the United States' vital mission is here, what is our vital interest, how does he see the potential cost unfolding here," said Rep. Candice Miller, R-Michigan, in an interview from her home district.

[6:32 p.m. Monday ET, 12:32 a.m. Tuesday in Libya] Frances Fragos Townsend, once President George W. Bush's chief counterterrorism adviser and now a CNN commentator, recalls her 2007 visit to the Gadhafi compound in Tripoli where coalition missiles heavily damaged a building on Sunday.

[5:25 p.m. Monday ET, 11:25 p.m. Monday in Libya] CNN's Ed Henry offers a deeper look at U.S. President Barack Obama's comments in Chile regarding Libya on Monday afternoon: Obama repeated Monday that Moammar Gadhafi "needs to go," but he acknowledged the Libyan dictator may remain in power for some time because the allied military mission in North Africa has a more narrow U.N. mandate of just protecting civilians.

Still, Obama noted: "I also have stated that it is U.S. policy that Gadhafi needs to go." Obama said he's still hopeful that other "tools" the administration has used, such as freezing billions in Libyan assets, will eventually help the Libyan people push Gadhafi out.

[5:10 p.m. Monday ET, 11:10 p.m. Monday in Libya] U.S. Sen. Mark Begich, D-Alaska, has expressed "apprehension" and "concerns" about U.S. involvement in Libya.

"Specifically, Congress needs to understand the risk involved to the lives of our service members, how long the administration anticipates U.S. involvement, the impact of our involvement on our other national security priorities like Afghanistan, and what the ultimate objective is," Begich, a member of the Senate's Armed Services Committee, said in a statement Monday.

[4:52 p.m. Monday ET, 10:52 p.m. Monday in Libya] U.S. Sen. Richard Lugar, who already had expressed concern about U.S. and allied air strikes in Libya, has amped up his criticism of the operation, saying "there are no guidelines for success."

In an interview set to air Monday on CNN's "John King, USA," Lugar, the ranking member of the Senate Foreign Relations Committee, said the operation has not been clearly defined.

"I do not understand the mission because as far as I can tell in the United States there is no mission and there are no guidelines for success," Lugar, R-Indiana, told CNN's John King. "That may well be true with our allies although conceivably they may have other missions in mind and simply try to get Security Council clearance to proceed."

[4:46 p.m. Monday ET, 10:46 p.m. Monday in Libya] Libyan leader Moammar Gadhafi's momentum has stopped and rebels have been able to hold onto areas that government forces had been poised to capture just a few days ago, a U.S. official said Monday.

However, an opposition spokesman said Gadhafi's forces have continued to fight in Mistata, the last city in western Libya under rebel control, despite the Libyan government's declaration of a cease-fire. "There is no cease-fire in Misrata," said Mohamed, who would not divulge his last name out of concern for his safety. "The destruction is unimaginable."

Late Monday, state television reported that Misrata was firmly in the hands of Libyan government forces.

[4:42 p.m. Monday ET, 10:42 p.m. Monday in Libya] The U.N. Security Council has decided to not take action Monday on Libya's request for an emergency meeting on attacks. Discussions will likely continue at a planned Thursday briefing on Libya by U.N. Secretary-General Ban Ki-Moon.

Libya's government is pressing for an end to what it calls an aggression against the country.

[4:08 p.m. Monday ET, 10:08 p.m. Monday in Libya] Oil prices surged in electronic trading Monday after coalition forces launched an attack on Libyan military targets over the weekend, CNNMoney reports.

The benchmark U.S. contract, West Texas Intermediate, gained as much as $2.28 to top $103 a barrel for April delivery. It later dropped back to settle $1.26 higher at $102.33 a barrel. The more active May contract jumped $1.24 to settle at $103.09 a barrel. It briefly topped $104 in earlier trading.

[3:47 p.m. Monday ET, 9:47 p.m. Monday in Libya] U.S. President Barack Obama is getting heat from a member of his own party regarding the military action in Libya.

Rep. Dennis Kucinich, the seven-term liberal Democrat from Ohio who has twice run for the White House, says Obama committed an "impeachable offense" in deciding to authorize U.S. airstrikes over Libya Saturday without the consent of Congress.

"President Obama moved forward without Congress approving. He didn't have Congressional authorization, he has gone against the Constitution, and that's got to be said," Kucinich told the web site Raw Story on Monday. "It's not even disputable, this isn't even a close question."

[3:33 p.m. Monday ET, 9:33 p.m. Monday in Libya] Below is a video of CNN's Nic Robertson, reporting on explosions that he heard this afternoon in Tripoli. He says he heard at least two blasts, apparently coming from the direction of Libyan leader Moammar Gadhafi's compound. Antu-aircraft gunfire followed the blast.

The new explosions come a day after a building in Gadhafi's compound was damaged in an apparent coalition airstrike.

[3:17 p.m. Monday ET, 9:17 p.m. Monday in Libya] Explosions were heard minutes ago in Tripoli, CNN's Nic Robertson reported.

Robertston, who is in Tripoli, said anti-aircraft gunfire has followed the explosions.

[3:08 p.m. Monday ET, 9:08 p.m. Monday in Libya] President Barack Obama, addressing the situation in Libya during a trip to Chile, told reporters that a condition for the United States to step back from leading the Libyan military mission is the disabling of Libya's air defenses. This is so that NATO allies and other coalition partners can effectively enforce a no-fly zone, he said.

"We anticipate this transition to take place in a matter of days, not weeks," Obama said.

[2:58 p.m. Monday ET, 8:58 p.m. Monday in Libya] U.S. President Barack Obama, addressing the situation in Libya during a trip to Chile, said that "it is U.S. policy" that Libyan leader Moammar Gadhafi "has to go."

Obama said the core principle of the military mission is that the international community "can't stand by with empty words" in the face of an imminent humanitarian catastrophe such as a leader using military force against his own people.

[1:45 p.m. Monday ET, 7:45 p.m. Monday in Libya] Four New York Times journalists who were reported captured by pro-government forces in Libya last week have been released and have arrived safely in Tunisia, the paper's Executive Editor Bill Keller said Monday in an e-mail obtained by CNN. "We're particularly indebted to the Government of Turkey, which intervened on our behalf to oversee the release of our journalists and bring them to Tunisia," Keller said in the e-mail which was sent to New York Times staff. "We were also assisted throughout the week by diplomats from the United States and United Kingdom."

[12:44 p.m. Monday ET, 6:44 p.m. Monday in Libya] There is no intent to destroy the Libyan military forces, Gen. Carter Ham, a top U.S. commander said Monday, but the coalition will strike against forces that are threatening or attacking civilians, he said.

[12:30 p.m. Monday ET, 6:30 p.m. Monday in Libya] The coalition flew 70 to 80 sorties over Libya on Monday, up from 60 on Sunday, said Gen. Carter Ham, commander of U.S. Africa Command. The United States flew fewer than half of the Monday missions and about half of the Sunday sorties, Ham said.

Canadian and Belgian air force planes flew for the first time Monday. "We are hopeful that other nations will continue to join us," Ham said. "Some have made very firm offers."

[12:26 p.m. Monday ET, 6:26 p.m. Monday in Libya] Libyan leader Moammar Gadhafi may remain the leader of Libya after the coalition mission has ended, the commander of U.S. forces said Monday.

"I could see accomplishing the military mission which has been assigned to me and the current leader would remain the current leader," Gen. Carter F. Ham, commander, U.S. Africa Command, said. "Is that ideal? I don't think anyone would say that that is ideal, but I could envision that as a possible situation - at least for the current mission that I have."

[12:19 p.m. Monday ET, 6:19 p.m. Monday in Libya] Coalition strikes not designed to kill Libyan leader Moammar Gadhafi, Gen. Carter Ham, commander of U.S. Africa Command, says.

[12:10 p.m. Monday ET, 6:10 p.m. Monday in Libya] There are no U.S. or coalition forces on the ground in Libya, Gen. Carter Ham, commander of U.S. Africa Command, says.

[12:05 p.m. Monday ET, 6:05 p.m. Monday in Libya] Coalition mission doesn't include protecting forces opposed to Libyan leader Moammar Gadhafi, Gen. Carter Ham, commander of U.S. Africa Command, said Monday.

[11:32 a.m. Monday ET, 5:32 p.m. Monday in Libya] Coalition members were still working out Monday how the ongoing of maintaining the no-fly zone over Libya would be commanded, U.S. officials said.

NATO could command the coalition's no-fly mission in Libya, but some Arab nations are hesitant to fly under a NATO banner, which has held up the move, said one official, who asked not to be identified due to the sensitivity of negotiations.

The coalition has 10 announced partners: Belgium, Britain, Canada, Denmark, France, Italy, Norway, Qatar, Spain and the United States.

[9:05 a.m. Monday ET, 3:05 p.m. Monday in Libya] The involvement of U.S. military aircraft in strikes on Libya has "plateaued," a spokesman for United States Africa Command says. The U.S. conducted missile strikes overnight, spokesman Vince Crowley said.

[8:23 a.m. Monday ET, 2:18 p.m. Monday in Libya] Four New York Times journalists who were reported captured by pro-government forces in Libya last week have been released and are in the Turkish Embassy in Tripoli, Turkey's ambassador to Libya, Levent Sahin Kaya, told CNN Monday. Read full story.

[7:18 a.m. Monday ET, 1:18 p.m. Monday in Libya] Oil prices surged more than $2 a barrel in electronic trading Monday after coalition forces launched an attack on Libyan military targets on Saturday. The benchmark U.S. contract, West Texas Intermediate, gained $2.11 to $103.18 a barrel for April delivery. The more active May contract jumped $2.21  to $104.06 a barrel.

[6:32 a.m. Monday ET, 12:32 p.m. Monday in Libya] The British Ministry of Defense said it halted a mission to attack a target in Libya because of information about civilians in the area.

"As the RAF GR4 Tornados moved into the area, further information came to light that identified a number of civilians within the intended target area," the ministry said in a statement Monday. "As a result the decision was taken not to launch weapons. This decision underlines the UK's commitment to the protection of civilians."

[6:02 a.m. Monday ET, 12:02 p.m. Monday in Libya] A witness in the Libyan city of Misrata reported "absolute destruction and carnage" by forces supporting leader Moammar Gadhafi on Monday - despite the regime's recent call for a cease-fire.

"Misrata is being flattened and razed to the ground as we speak," said the man, who was not identified safety reasons. "He (Gadhafi) is using tanks and snipers to terrorize the city."

He added, "They are shooting people in the main street and on the back street."

CNN could not independently confirm reports from Misrata early Monday.

[5:57 a.m. Monday ET, 11:57 a.m. Monday in Libya] A group of supporters of Libyan leader Moammar Gadhafi chanted "Down with the USA" and confronted UN Secretary-General Ban Ki-moon as he was leaving the Arab League buidling in Cairo on Monday, a UN spokesman said.

Spokesman Khawla Mattar said Ban was "fine" and "it was not a serious incident." "They were not chanting anti-UN slogans. They were probably just trying to send a message through the UN," he said.

[4:21 a.m. Monday ET, 10:21 a.m. Monday in Libya] The French government disputed claims of civilian deaths in Libya from recent airstrikes.

"There is no information of killed civilians recorded by the French command," French government spokesman Francois Baroin said on the French TV channel Canal+ Monday.

Libyan ruler Moammar Gadhafi's regime claimed that dozens of people - mostly women, children and clerics - have been killed in the international airstrikes that started Saturday.

"We must be cautious of communication campaigns and propaganda. ... This is a military operation and a communications campaign battle," Baroin said. "We have to trust what the international community is communicating."

[2:14 a.m. Monday ET, 8:14 a.m. Monday in Libya] U.S. Secretary of Defense Robert Gates said it would be "unwise" to set specific goals about targeting Libyan leader Moammar Gadhafi directly during attacks.

"I think that it's important that we operate within the mandate of the U.N. Security Council resolution," Gates told reporters Sunday while on a plane to Russia. "If we start adding additional objectives, then I think we create a problem in that respect.  I also think that it is unwise to set as specific goals, things that you may or may not be able to achieve."

The Security Council resolution, which passed Thursday, allows member states "to take all necessary measures to protect civilians under threat of attack in the country ... while excluding a foreign occupation force of any form on any part of Libyan territory," according to the United Nations.

[12:34 a.m. Monday ET, 6:34 a.m. Monday in Libya] A coalition military official has confirmed that Libyan leader Moammar Gadhafi's compound was targeted by airstrikes Sunday night. The compound was targeted, the official said, because it contains capabilities to exercise command and control over Libyan forces and the coalition goal is to degrade his military capabilities. Earlier, Western journalists, including CNN's Nic Robertson, were brought inside the compound to survey the destruction.

[10:51 p.m. Sunday ET, 4:51 a.m. Monday in Libya] An announced list of the countries participating in the military coalition: The United States, Belgium, Britain, Canada, Denmark, France, Italy, Norway, Qatar and Spain.

U.S. officials have said they plan to hand over operational control of the military mission in coming days.