WASHINGTON (AP) -- When it comes to Syria, the Obama administration is sure about one thing: President Bashar Assad's government must be punished after allegedly using deadly chemical weapons, possibly including sarin gas, to kill hundreds of Syrians.
The U.S. and allies accuse Assad of crossing a line that President Barack Obama said would have "enormous consequences." That's now expected to trigger a military strike, limited in time and scope, with the goal of downgrading and weakening Assad but not toppling him or destroying his forces.
The details of how and when the U.S. military and allied forces might attack are under debate but would be based on complex plans developed and repeatedly reworked over time by the Pentagon. They could further be complicated by Obama's decision to seek authorization from Congress for the use of force.
A look at what's known and what's unclear about how it might unfold.
The order for the strike would come from Obama, delivered to Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, and Defense Secretary Chuck Hagel. The operation probably would fall under the purview of U.S. Central Command, headed by Army Gen. Lloyd Austin. The more immediate commander probably would be Adm. Bruce Clingan, who heads U.S. naval forces in Europe.
U.S. commanders would communicate and coordinate with military officers from other nations involved in the fight, such as France.
WHO LAUNCHES WHAT
Five U.S. Navy destroyers -- the USS Gravely, USS Mahan, USS Barry, the USS Stout and USS Ramage -- are in the eastern Mediterranean Sea waiting for the order to launch. And the USS San Antonio, an amphibious assault ship has now joined them. The USS San Antonio, which is carrying helicopters and Marines, has no cruise missiles, so it is not expected to participate in the attack. Instead, the ship's long-planned transit across the Mediterranean was interrupted so that it could remain in the area to help if needed.
The destroyers are armed with dozens of Tomahawk cruise missiles, which have a range of about 1,000 nautical miles and are used for deep, precise targeting. Each one is about 20 feet long and less than two feet in diameter and carries a 1,000 pound warhead.
The missiles fly at low altitudes, and their range allows the ships to sit far off the coast, out of range of any potential response by the Syrian government. Some ships have cameras that can provide battle damage assessments.
The Navy also now has two aircraft carriers in the Arabian Sea that are loaded with fighter jets. The USS Truman arrived in the region to take the place of the USS Nimitz, which was supposed to head home. But the Navy ordered the Nimitz to stay for now.
U.S. officials described the decision as prudent planning and said it doesn't suggest the Nimitz would play a role in any possible strikes in Syria.
With Britain on the sidelines, France has said it is preparing for military action against Syria. French President Francois Hollande does not need parliamentary approval to launch a military operation that lasts less than four months.
French military officials confirmed the frigate Chevalier Paul, which specializes in anti-missile capabilities, as well as the hulking transport ship Dixmude, had set off Thursday from the Mediterranean port of Toulon as part of normal training and operational preparations -- but denied any link to possible Syria operations.
France also has a dozen cruise missile-capable fighter aircraft at military bases in the United Arab Emirates and the Horn of Africa nation of Djibouti, as well as fighters that could launch from air bases in the French island of Corsica or western France.
HOW DO THE NATIONS COORDINATE?
Details are unknown about how the mission strikes are being allocated or if the U.S. and France have mapped out separate, agreed upon target lists. But the U.S. routinely conducts exercises with allies, particularly NATO countries such as Britain and France, in which they all practice exactly this type of joint attack mission.
Commanders have a wide variety of ways they can talk to each other, including through integrated communications systems honed over many years of NATO operations ranging from the Afghanistan war to the 2011 attack on Libya and the fighting in Algeria and Mali early this year.
The military officers can speak or email across classified, secure lines and even have systems that allow them to talk in real time in Internet chat rooms. The nations also often have military liaisons embedded with each other to help assist communications.