TAIPEI, Taiwan — Taiwan’s government expressed concern on Friday hours after a call between China and the United States’ top diplomats in which Beijing stressed that self-ruled Taiwan was the biggest risk in relations.

“Taiwan’s Ministry of Foreign Affairs is concerned about the press release issued by China … which again unilaterally made threatening remarks on the Taiwan issue,” the Foreign Ministry said in a statement.

In a call with U.S. Secretary of State Marco Rubio Thursday, Chinese Foreign Minister Wang Yi urged the United States to “make the right choices” on Taiwan in order to safeguard “stability” between the two nations, according to a statement by the Chinese Foreign Ministry.

The call came about two weeks ahead of a highly anticipated summit between U.S. President Donald Trump and Chinese leader Xi Jinping, in which Taiwan is expected to be one of the key topics.

China sees self-ruled Taiwan as its own breakaway province, to be retaken by force if necessary. In recent years China has ramped up military pressure on the island by sending warships and military planes near it almost daily.

Beijing also prohibits all its diplomatic partners from maintaining formal ties with Taipei.

The United States, while not recognizing Taiwan as a country, is the island’s strongest backer and arms provider.

Trump had previously suggested he would discuss arms sales to Taiwan with Xi, a statement that raised concerns on the island.

Taiwan’s Foreign Ministry on Friday added that China has “recently continued to escalate pressure on Taiwan,” referring to allegations that Beijing disrupted a planned visit by Taiwan’s president to Africa last month.

President Lai Ching-te was forced to postpone a visit to Eswatini in late April after three countries withdrew permission for him to fly over their territories due to pressure from China, according to his office.

China did not confirm nor deny the allegations but instead expressed “high appreciation” for the actions, saying the “relevant countries’ adherence to the one-China principle is in full compliance with international law,” in reference to Beijing’s claims over Taiwan.