TAIPEI, Taiwan (AP) — Taiwanese President Tsai Ing-wen reviewed military drills Friday ahead of planned war games by China amid rising tensions between the rivals.

Tsai went aboard a U.S.-made destroyer in the port of Su’ao as the island’s armed forces simulated breaking a blockade of the self-ruled island.

China, which claims Taiwan as its territory, has scheduled live-fire war games in the Taiwan Strait for next Wednesday. That follows Beijing’s heated objections to U.S. moves to strengthen relations with Taiwan’s democratic, independence-leaning government.

Despite a lack of formal ties, Washington is legally bound to respond to threats to Taiwan and is the island’s main supplier of foreign military hardware.

Chinese officials have denounced the recent passage of a U.S. law encouraging more high-level government contacts with Taiwan, saying that violates U.S. commitments not to restore formal exchanges severed when Washington switched diplomatic recognition from Taipei to Beijing in 1979.

An agreement to provide Taiwan with submarine manufacturing technology and the appointment of hawkish National Security Adviser John Bolton have also hardened views among anti-America nationalists in China.

In a reiteration of China’s military resolve, President Xi Jinping spoke about the importance of naval power while attending a massive fleet review on Thursday in the South China Sea.

“The mission of building a mighty people’s navy has never been more urgent than it is today,” Xi, dressed in army fatigues, said in remarks delivered on the helicopter deck of one of China’s most advanced destroyers. “Strive to make the people’s navy a first-rate world navy.”