The United States opened international aid offices in the Pacific Islands this week, bolstering support for the strategic region and pitting it more forcefully against China, which has been providing infrastructure loans to the area for years.

The vast ocean region, pivotal in World War II, is in the spotlight again amid tensions over Taiwan. Taiwanese officials this week said China, which claims the island as its territory, could launch military drills soon to intimidate voters ahead of an election next year.

On Wednesday, a Chinese military delegation joined a U.S.-hosted conference of two dozen international defense chiefs in Fiji, highlighting the region's importance to both superpowers.