The island chain strategy is a strategic maritime containment plan first conceived by American foreign policy statesman John Foster Dulles in 1951, during the Korean War. It proposed surrounding the Soviet Union and China with naval bases in the West Pacific to project power and restrict sea access.

The "island chain" concept did not become a major theme in American foreign policy during the Cold War, but after the dissolution of the Soviet Union has remained a major focus of both American and Chinese geopolitical and military analysts to this day. For the United States, the island chain strategy is a significant part of the force projection of the U.S. military in the Far East. For the People's Republic of China (PRC), the concept is integral to its maritime security and fears of strategic encirclement by the U.S. and its allies. For both the U.S. and the PRC, the island chain strategy emphasizes the geographical and strategic importance of Taiwan.

The US has around 750 overseas bases in about 80 countries, while China has one anti-piracy support base in Djibouti.

A couple of graphs from elsewhere:

This one is a little dated: we’re no longer in Afghanistan:

“Forward defense ring,” a perfectly normal and not at all Orwellian term of art 🤨