Taiwan President Tsai Ing-wen praised military cooperation with the United States on Thursday, as she commissioned the first combat wing of F-16 aircraft refurbished with American assistance to reinforce the island’s defenses amid escalating tensions between Taipei and Beijing.

Frequent Chinese and American military exercises in the region have fueled concerns of conflict, sparked by a dispute over democratically-ruled Taiwan, which Beijing claims as its own territory.

Tsai said at a ceremony in the southern Taiwanese city of Chiayi to present the first squadron of its most sophisticated F-16s, the F-16V, saying the project demonstrated the Taiwan-US partnership’s unwavering commitment.

“I believe that as long as we adhere to democratic and free values, there will be more like-minded countries standing alongside us,” she added, appearing on the same stage as the top US diplomat in Taiwan, Sandra Oudkirk.

To Beijing’s chagrin, the United States has no official diplomatic ties with Taiwan but is the island’s principal international backer and weaponry supplier.

The T$110 billion ($3.96 billion) F-16 upgrade is led by manufacturer Lockheed Martin Corp and Taiwan’s Aerospace Industrial Development Corp (AIDC), and is the latest example of military cooperation between Washington and Taipei.

Taiwan has been converting 141 F-16A/B jets into the F-16V type, 64 of which have already been upgraded, and has additionally ordered 66 new F-16Vs, which have new avionics, weapons and radar systems to better face down the Chinese air force, including its J-20 stealth fighter.

The F-16Vs can carry Raytheon Technologies Corp’s advanced AIM-9X Sidewinder air-to-air missiles.

To a backdrop of dance music broadcast over the air base, the F-16s showed off their mettle with combat take offs and landings, and flying low in formation above the runway.

Tsai said that as more F-16Vs entered service, Taiwan’s defenses would be “even stronger”.

Taiwan’s air force is well trained but dwarfed by China’s.

The United States in 2019 approved an $8 billion sale of F-16 fighter jets to Taiwan, a deal that would take the island’s F-16 fleet to more than 200 jets, the largest in Asia.

China has announced sanctions on Lockheed Martin for selling arms to Taiwan.