A Chinese maritime militia vessel has been spotted for the first time off Taiwan's Pacific coast, and Washington is calling the move highly destabilizing — a bad sign for regional calm.

• A fishing boat that doubles as a Chinese militia ship was tracked in August near Taiwan's east coast, sailing alongside a Chinese coast guard ship and a research vessel.
• It is the first time such a vessel has turned up in this sensitive area, which sits away from the usual flashpoint in the Taiwan Strait.
• The US State Department said it remains concerned about Chinese activity east of Taiwan and urged Beijing to stop pressuring the island.
• Taiwan's coast guard says the ships stayed outside restricted waters and were watched the whole time.
• Taiwan's defense ministry accused Beijing of dressing up intrusions as law enforcement and science work to fake a claim of control over the waters.

Outlook: Expect more of these quiet probes east of Taiwan as Beijing tests how far it can push without triggering a confrontation.