China’s military has doubled the size of its Amphibious Mechanized Infantry Division (AMID) from about 30,000 to 60,000 men for a potential conflict in the East and South China seas as well as with Taiwan, according to Taiwan-based news site Want China Times. The AMIDs are fit for a large-scale amphibious invasion, but China still lacks the conventional amphibious transportation required to cross the Taiwan Strait, according to a 2014 Pentagon report on the People’s Liberation Army (PLA).

“An attempt to invade Taiwan would strain China’s armed forces and invite international intervention,” the report stated. “The PLA is capable of accomplishing various amphibious operations short of a full-scale invasion of Taiwan. With few overt military preparations beyond routine training, China could launch an invasion of small Taiwan-held islands in the South China Sea such as Pratas or Itu Aba. A PLA invasion of a medium-sized, better defended offshore island such as Matsu or Jinmen is within China’s capabilities.”

Although each of the now-four AMIDs are equipped with 300 armored and amphibious transport vehicles, these vehicles cannot cross large areas of water like the Taiwan Strait. China would have to use its amphibious assault ships, such as the new Type 071 transport ship, which can carry between 15 to 20 armored vehicles and 500 to 800 troops. But all of these ships combined could not carry and resupply a single AMID along with provisions across seas, according to the Diplomat.

However, reports in 2013 claimed that China is building its first amphibious assault ship capable of transporting multiple hovercraft and helicopters, according to Japan’s Kyodo News International. A 2008 Pentagon report said the Chinese military was increasing its mobility in the event of a conflict with Taiwan, according to the Want China Times.

Taiwan’s former marine corps colonel Yi-Jia Shiah told the Want China Times that doubling the AMIDs is not necessarily a greater threat to the island, because the PLA’s AMIDs and marine corps have yet to establish a joint command system. As a lone unit, the AMIDs have insufficient battle experience at sea and cannot rely on their current amphibious assault fleet. The marine corps, however, is focused on “sea-to-sea” warfare. Thus, cooperation between the two units will be closely watched, Shiah told the Want China Times on Sunday.

Mainland China has eyed the island of Taiwan and other strategic isles in the region for decades.

The Republic of China (ROC), a nationalist government, lost the Chinese Civil War against the Communist Party in 1949. The ROC fled to the island of Taiwan while the Communist Party took control of mainland China, establishing the People’s Republic of China (PRC). The ROC currently governs Taiwan and surrounding isles as well as islands in the South China Sea. However, the PRC has for long claimed sovereignty over Taiwan as its twenty-third province and refuses to recognize the ROC as Taiwan’s governing body.

The PRC has threatened military force if peaceful unification is ultimately rejected or if official Taiwanese independence is declared, according to the U.S. Department of State’s Office of the Historian.