A U.S. Coast Guard cutter crossing the Tasman Sea as part of maritime security cooperation with Australia and New Zealand knew Chinese naval ships were in the area but had no interaction with them, its commanding officer said on Tuesday.

The drills, conducted near a busy air corridor, have prompted both countries to enhance surveillance and collaborate with allies.

When geopolitical tension mounts, New Zealand tends to lean closer to traditional allies. Chinese warships in the Tasman make that even likelier now.