A major defense cooperation pact between the US and Indonesia is reported. While diplomatic statements are cautious, experts suggest the agreement significantly influences regional power dynamics and maritime security.

Indonesia says it is not choosing sides. That is true in diplomacy. It is less true on the map. The “major defence cooperation partnership” announced by Washington and Jakarta on April 13 is written in the safe language of official communiques: capacity building, education, exercises, cooperation. But the harder meaning lies beneath the phrasing. The most important line in this new defence partnership is not the reassuring one about “peace and stability”. It is the one about “maritime,...