If President Barack Obama decides to take military action against Syria for using chemical weapons in its two-year-old civil war, the initial blows likely would be delivered by four U.S. guided missile destroyers currently in the Mediterranean.
Beyond that, the president has a number of other ships and aircraft, both in the region and elsewhere, that he could use to carry out limited strikes to send a message aimed at deterring further chemical weapons use.
In the event of a decision to carry out strikes against Syria, European allies like Britain and France are likely to support the effort using their own stand-off weapons like the jointly developed SCALP/Storm Shadow air-launched cruise missile.
Following are some of the U.S. military assets at Obama's disposal:
GUIDED MISSILE DESTROYERS - The United States has four guided missile destroyers in the eastern Mediterranean Sea - the USS Gravely, the USS Barry, the USS Ramage and the USS Mahan. The ships can carry a maximum of 90 to 96 Tomahawk cruise missiles if loaded only with those weapons. The actual number they are carrying at any time depends on the mission and what other weapons and systems are needed. Tomahawk missiles are likely to be the weapon of choice if Obama orders a strike on Syria because they have a range of about 1,000 miles (1,610 km) and can be used at a distance without a concerted effort to destroy Syria's integrated air defenses.
SUBMARINES - The United States has 58 submarines capable of launching Tomahawk cruise missiles, including four specifically designated guided missile submarines capable of carrying up to 154 missiles apiece. The Navy does not discuss the whereabouts of its submarines, but one or more could be tapped for duty if Obama decides to carry out targeted strikes against Syria.
AIRCRAFT - U.S. B-1, B-2 and B-52 bombers are capable of carrying conventional air-launched cruise missiles. Those could be called into play if needed, as they have been in previous conflicts in the Middle East, flying from bases in the United States or elsewhere. The air-launched cruise missiles also are stand-off weapons that could be dropped from outside Syrian territory.
AIRCRAFT CARRIERS - The USS Harry S. Truman is currently in the northern Arabian Sea and the USS Nimitz is in the Indian Ocean. Aircraft from the two carriers could be called into service if needed to participate in an attack against Syria. But their participation appears unlikely. U.S. officials have indicated any strikes against Syria are likely to be limited in scope. Use of aircraft from the carriers would probably require a broader operation involving a U.S. effort to destroy Syria's integrated air defenses before sending planes over the country. The Nimitz has been supporting U.S. operations in Afghanistan and is due to be replaced by the Truman, which is crossing the Arabian Sea to relieve the Nimitz so it can return home.
AMPHIBIOUS ASSAULT SHIP - The USS Kearsarge just ended a port call in the Gulf and is headed back out to sea. The vessel has a contingent of Marines but is not considered likely to participate in limited operations like the ones Obama is reported to be considering.
ADDITIONAL AIRCRAFT AT BASES IN THE REGION - The United States has additional aircraft at different bases in the region that could support an operation against Syria if needed. But that is not seen as likely because it would require a much larger effort to remove the threat of Syria's air defenses. (Reporting by David Alexander; Editing by Karey Van Hall and Jim Loney)