Naval forces: Two aircraft carriers, the USS Constellation and the USS Abraham Lincoln are in the Persian Gulf, and the USS Harry S Truman is in the Mediterranean Sea.
The USS Theodore Roosevelt has also recently deployed for the region, and the USS Kitty Hawk is reportedly on its way to the Gulf from the Far East.
About 5,000 personnel and 75 warplanes are stationed aboard each carrier. Each vessel is accompanied by half a dozen cruisers, destroyers and submarines equipped with Tomahawk cruise missiles.
The British aircraft carrier HMS Ark Royal is due to pass through the region en route to the Far East. Several other UK ships, including the helicopter carrier HMS Ocean, could also be deployed.
Supply and assault ships: Nine cargo ships, which together can carry roughly a divisions worth of heavy equipment, are expected to set sail from various US ports in late January. Five amphibious assault ships carrying a force of about 4,000 Marines are on their way to the Gulf.
