Philippines President Ferdinand Marcos Jr. is fighting a battle on two fronts with China: One in the South China Sea and the other as a proxy for the US over Taiwan. It is one of the reasons the mainland is so keen to weaken the Philippines — because it also means weakening Taipei. There is strength in unity: Teaming up against Beijing could help the two smaller parties battle a much stronger opponent.

Their fates are inextricably linked. Many of the Philippines’s islands are less than 100 kilometers (62 miles) from Taiwan. Both are part of the First Island Chain, a string of Washington-friendly governments in the Pacific. The imaginary line, drawn between the islands of Japan, then passing Taiwan and the Philippines and curving at the southern end of the South China Sea between Malaysia and Vietnam, has been a key pillar of American military strategy since the 1950s. On geography alone, a Chinese invasion of Taiwan would have serious implications for Manila.