The United States shipped 2.5 million Covid-19 vaccine doses to Taiwan on Saturday, more than tripling Washington's previous allocation of shots for the island, which has faced increasing political and military pressure from China.

Washington, competing with Beijing to deepen geopolitical clout through so-called "vaccine diplomacy," initially had promised to donate 750,000 doses to Taiwan but increased that number as President Joe Biden's administration advances its pledge to send 80 million US-made shots around the world.

China, which considers Taiwan an integral part of its territory, has repeatedly offered to send coronavirus vaccines to the island, which has been battling a spike in domestic infections. Taipei has expressed concern about the safety of Chinese shots.