Ten Chinese aircraft crossed the median line of the Taiwan Strait, normally an unofficial barrier between the two sides, Taiwan’s defense ministry said on Saturday, as Beijing continues its military activities near the island.

Nine Chinese fighter jets and one military drone crossed the median line in the 24 hours to 6 a.m. on Saturday (6 p.m. ET), the ministry said in its daily report on Chinese military activities.

Taiwan scrambled its own jets to warn away the Chinese aircrafts, while missile systems monitored them, the ministry said, using standard wording for its response.

Taiwan, which China claims as its own territory despite the island’s objections, has complained in recent years of almost daily missions by the Chinese air force near the democratically governed island, often in the southwestern part of its air defense identification zone.

Beijing has threatened unspecified retaliation if Taiwan President Tsai Ing-wen, now travelling in the Americas, should meet U.S. House of Representatives Speaker Kevin McCarthy. She is expected to meet him in Los Angeles on her way back to Taipei this month from Central America.

China staged war games around Taiwan in August after then-Speaker Nancy Pelosi visited Taipei, and has continued military activities near Taiwan, though on a reduced scale.

A senior Taiwan official familiar with the island’s security planning told Reuters this week China was unlikely to repeat such large exercises, but all preparations were made in case China reacts “irrationally”.

Separately, nine Chinese aircraft crossed the median line on Friday carrying out combat readiness patrols, a move that Taiwan’s defense ministry said has “deliberately created tension” and undermined peace and stability.