(CNN) -- An international military coalition including France, the United States and Great Britain attacked Libyan air-defense and other military targets Saturday night in an operation that eventually will include enforcing a no-fly zone.
Libyan rebels had called on international action to help them stave off assaults by Libyan government forces on their positions in Benghazi and other enclaves. The coalition's intervention in Libya's civil war comes two days after the U.N. Security Council passed a resolution authorizing the use of force, including a no-fly zone, to "protect civilians and civilian populated areas" from government attack.
Here is a look at how the situation got to this point, and what the major players are saying and doing.
THE START OF THE CONFLICT
Libya's civil war began last month, following protests that coincided with a larger wave of demonstrations in North Africa and the Middle East against governments there.
In Libya, protesters rallied against, among other things, high unemployment and a delay in a government housing project, and they eventually called for democracy and an end to Moammar Gadhafi's almost 42-year-long rule. Clashes between protesters and security forces began in Benghazi -- Libya's second-largest city -- on February 16, and as violence spread to other cities, opposition forces claimed control of Benghazi and other parts of eastern Libya.
In the ensuing days, the opposition and external governments accused the Libyan regime of atrocities and rights violations, including allegations of a military helicopter firing on a crowd in Benghazi, other military attacks against civilians, arbitrary detentions and summary executions. Gadhafi's regime responded that it was attacking al Qaeda, not civilians.
GADHAFI'S FORCES GAIN GROUND AGAINST REBELS
At the beginning of March, the Libyan military stepped up efforts to reclaim areas lost to rebels.
Pro-Gadhafi forces marched eastward, hammering rebel positions in north-central Libya's Ras Lanuf by the end of last week and moving on to al-Brega and Ajdabiya. By the end of this week, Gadhafi's forces were poised to strike Benghazi.
ARAB LEAGUE REQUESTS NO-FLY ZONE; U.N. COMPLIES
While the rebels pleaded for help, late last week, the Arab League voted to ask the United Nations Security Council to impose a no-fly zone over Libya to "protect the civilian population," league Secretary General Amre Moussa said.
On Thursday, a day when Gadhafi's forces launched air strikes on Benghazi's airport, the U.N. Security Council voted 10-0, with five nations abstaining, to impose a no-fly zone and permit "all necessary measures" to protect civilians. The measure prohibited "a foreign occupation force of any form on any part of Libyan territory."
LIBYAN GOVERNMENT DECLARES CEASE-FIRE; FIGHTING CONTINUES
Hours later, the Libyan government declared an immediate cease-fire, but fighting continued to be reported in parts of the country. France, Britain, the United States and Arab League nations warned Gadhafi to stop his operations immediately.
On Saturday, Gadhafi's forces assaulted Benghazi, with witnesses saying artillery rounds landed inside the city and tanks rolled into town, firing. Civilians said buildings came under small-arms fire. An opposition spokesman said that Gadhafi's forces then repositioned themselves far outside the city, and that "tens" of people in the city had been killed during the assault.
French fighter jets that were deployed over Libya fired at a military vehicle Saturday as the international coalition's military response began.
U.S., BRITAIN LAUNCH FIRST MISSILES
With Western leaders saying Gadhafi hadn't heeded the U.N. resolution and warnings to stop attacks, American, French and British forces got to work Saturday night. Along with the French jet attack, American and British ships fired more than 110 Tomahawk missiles from ships and submarines, hitting about 20 Libyan air and missile defense targets in an operation dubbed Odyssey Dawn, U.S. Vice Adm. William Gortney said at a Pentagon briefing.
"What we are doing is necessary, it is legal and it is right," British Prime Minister David Cameron said. "I believe we should not stand aside while this dictator murders his own people."
There were no U.S. warplanes flying over Libya late Saturday, but a coalition -- including the United States, Britain, France, Canada and at least two Arab nations -- was preparing to enforce a no-fly zone, Gortney said.
The coalition is expected to continue targeting air and missile defense targets over the next couple of days so jets enforcing the no-fly zone can fly more safely.
A senior U.S. official emphasized to CNN that President Barack Obama is privately planning for the U.S. portion of the military action in Libya to last for only a few days.
"In terms of the heavy kinetic portion of this military action, the president envisions it as lasting days, not weeks," said the senior official, who spoke on the condition of anonymity because he was not authorized to speak publicly about sensitive military planning. "After that, we'll take more of a supporting role."
The Libyan government is saying that it is being illegitimately targeted.
Hours after coalition forces launched the first wave of attacks against his military forces, Gadhafi said his people would fight back against undeserved "naked aggression." Libyan state TV broadcast Gadhafi's response, which included a call for people to take arms in the "war zone."
A Libyan government spokesman said Saturday that instead of sending international observers to witness a cease-fire, a coalition of international allies chose military aggression.
Earlier Saturday, Gadhafi issued defiant letters to international powers. "I have all the Libyan people with me, and I'm prepared to die. And they are prepared to die for me. Men, women and even children," Gadhafi said in a letter addressed to Obama and read to reporters by a government spokesman in Tripoli.
Gadhafi defended his actions in his note to Obama. He said his opponents are from al Qaeda in the Islamic Maghreb, the group's North African wing, and asked Obama what he would do if such an armed movement controlled American cities.
"Tell me, how would you behave so I could follow your example?"
Gadhafi -- in a separate letter addressed to Cameron, French President Nicolas Sarkozy and U.N. Secretary-General Ban Ki-moon -- called the U.N. moves "invalid" because the resolution does not permit intervention in the internal affairs of other countries.
"Libya is not yours. Libya is for all Libyans," said the letter, also read by the spokesman. "You will regret it if you take a step toward intervening in our internal affairs.
"It is not your country. We could never and would never fire one bullet against our people," the letter said.
The CNN Wire Staff contributed to this report.