With tensions in the South China Sea simmering — and getting hotter (the People's Liberation Army Navy stole an American underwater drone) — the chances that America and China could come to blows are increasing. The fight could very likely be a naval-air fight, but there could also be the need for something not really seen since the Korean War: amphibious assaults.
The United States has the world's preeminent military force in that capacity: The United States Marine Corps.
The People's Republic of China turns to the People's Liberation Army Navy Marine Corps for its needs in this area. These two forces are similar in that both have a mission to deploy by sea to carry out operations on land.
The Chinese force, though, consists of two brigades in the South China Sea area, totaling 12,000 active-duty personnel, according to GlobalSecurity.org. Calling up reserves could boost the force to 28,000.
That force is arguably outmatched by the USMC's III Marine Expeditionary Force (MEF), based out of Okinawa. A typical MEF has over 50,000 Marines, and features both a division and an air wing.
The Chinese Marines are equipped with armored vehicles, notably the Type 59 main battle tank and the Type 63A amphibious tank. The former is a knockoff of the Soviet T-55, carrying a 100mm gun.
The latter is an interesting design, equipped with a 105mm main gun, which holds 45 rounds, but capable of swimming to shore. China also has large stocks of Soviet-era PT-76 and indigenous Type 63 amphibious tanks in its inventory as well.
The Marines have the M1A1 Abrams tank, which is not amphibious. That said, this is a very tough tank that has deflected shells from more powerful tank guns from 400 yards. Against the Type 63A, it would easily survive a hit and then dispatch the tank that shot at it.
While the Type 63A can swim to a battlefield, it trades protection for that ability. The result is that its thin armor can be easily penetrated, and that is bad news for its crew.
The tank disparity is not all that would hamper the Chinese Marines. The People's Liberation Army Navy did not see fit to provide the Chinese Marines with any organic aviation. III Marine Expeditionary Force has the 1st Marine Air Wing, a powerful force that includes a squadron of F/A-18D Hornets, KC-130J tankers, and AH-1Z attack helicopters. That does not include units that rotate in from the United States, including AV-8B Harriers and F/A-18C Hornets.
In short, the United States Marine Corps brings in over 240 years of tradition, as well as far greater manpower, resources and capabilities. At present, if the United States wants China off of its unsinkable aircraft carriers, the American leathernecks would, in all likelihood, succeed.