China coast guard presses commercial ships off Taiwan as sightings jump 83%

In June, Taiwan detected 55 Chinese coast guard and research ship sightings around the island. That is up from 30 in May and more than double the 25 sightings recorded a year earlier, according to Taiwan's Coast Guard Administration.

The surge brought a new move. China's coast guard ships began broadcasting questions directly to cargo ships, demanding port entry and exit information. No ship changed course. Taiwan's Coast Guard Administration told mariners to hold their heading and ignore the Chinese broadcasts.

"It knows it has no jurisdiction now, so it is trying to create something out of nothing," a Taiwanese official said.

The patrol east of Taiwan traces back to June 1, when a Chinese coast guard formation sailed into open Pacific waters southeast of the island and claimed what Beijing calls a law enforcement zone. Taiwan and a number of other governments reject that claim.

A second group rotated in on July 4. Those ships switched off their automatic identification systems within roughly 24 hours of arriving. Maritime trackers lost their positions soon after the switch-off.

Taiwan is now preparing exercises off its Pacific coast designed to simulate Chinese escalation scenarios, officials said. The concern is that persistent CCG presence along Taiwan's eastern waters could be used to disrupt or intercept supply lines linking the island to allies across the Pacific.