“The country must rely on itself, and if any friends or other groups can help us, then it’s like I said before, we’re happy to have it, but we cannot completely depend on it,” Chiu said Thursday.

Tension between China and Taiwan has continued to rise, with Chiu calling the climate the most “severe” in 40 years as China has sent a record-breaking amount of fighter jets toward international airspace near the island and intensifying a campaign of military harassment. According to Chiu, at this rate, China would have “comprehensive” capabilities to invade the island in 2025.

The U.S. currently has a policy of “strategic ambiguity” with Taiwan, holding a vague stance on whether or not it would defend Taiwan. But last week, President Joe Biden said the U.S. was committed to protecting the island if China attacked it.

Taiwanese President Tsai Ing-wen said in an interview with CNN on Thursday that she is confident that the U.S. will help defend the island if China attacked.

“I do have faith given the long-term relationship we have with the U.S. and also the support of the people of the U.S. as well as Congress,” Tsai said.

As tensions continue to grow, China strongly opposes military exchanges between Taiwan and the U.S.

“If the U.S. continues to stubbornly cling to the illusion of using Taiwan to contain China…China will resolutely counter and fight back,” Chinese Defense Ministry spokesperson Tan Kefei said.

For more reporting from the Associated Press, see below.

China claims Taiwan as part of its national territory although the island has been self-ruled since it split from the communist-ruled mainland in 1949 after a long civil war.

Tsai also confirmed the presence of a small number of U.S. troops on the island to help train their Taiwanese counterparts.

Although the U.S. has no formal diplomatic relationship with the Taiwanese government, it has strong unofficial ties. Under the Trump administration, the U.S. stepped up weapon sales to Taiwan.

China’s Ministry of Foreign Affairs spoke out against the confirmation of troops, saying it is “firmly opposed to any form of official contacts and military ties” between the U.S. and Taiwan, and that no one should “underestimate the strong determination, firm will and strong capacity” of China to defend its sovereignty.