China has suspended all air traffic to Taiwan over a disputed island chain that it sees as part of its territory, the country’s foreign ministry said on Thursday.

The announcement came after Taiwan President Tsai Ing-wen visited Beijing on Friday and met with Chinese Foreign Minister Wang Yi.

China sees Taiwan as part “of its territory,” a claim it disputes.

Air traffic to and from Taiwan has been restricted since last month, when Tsai visited the mainland and the Chinese government imposed restrictions on all commercial flights between the two sides.

It said the decision to suspend air traffic would allow authorities to prepare for the arrival of Chinese ships to inspect the islands.

Tsai is scheduled to meet with Wang on Thursday and is expected to reiterate Beijing’s stance that Taiwan is part of China, a position that China considers unacceptable.

Taiwanese activists have been staging protests over the past few weeks over the island’s status, saying Beijing has no intention of returning control to Taiwan’s people.

A senior official in Taiwan’s foreign affairs ministry told Reuters the suspension of air traffic between Taiwan and China was not related to the island issue, but was in line with the Chinese foreign ministry’s policy.

Beijing has long insisted that Taiwan’s claims to the islands are “irrelevant” and that China has no intentions of returning them.

Taipei’s Taiwan Affairs Office on Wednesday urged China to “immediately cease” any efforts to undermine the sovereignty and territorial integrity of Taiwan and to allow the island to reunify with the mainland, which has long ruled the island.

(Reporting by Lee Hong-man; Editing by Leslie Adler)