Photo/Illutration A U.S.-made F-16V fighter jet takes off during military exercises in Chiayi county, southern Taiwan, on Jan. 15. (AP Photo)

CHIAYI, Taiwan—An alarm sounds and the pilots rush to their jets, sitting at the ready under a hardened shelter in the warm winter sun of southern Taiwan.

Their scramble into the air was only a drill before an audience of journalists. But for Taiwan’s Air Force and its most advanced fighters, the newly upgraded F-16V, the threat from China across the narrow Taiwan Strait is very real.

Surrounded by farmland near the coast, the Chiayi air base is Taiwan’s first to be equipped with F-16Vs, which carry upgraded radars, avionics and will eventually field new air-to-air missiles.

Chiayi’s F-16 pilots are on call around the clock to see off the Chinese jets that regularly try to probe the airspace of the democratic island China claims as its territory, to be taken by force if needed.

“If anything happens and we’re needed, we can scramble,” said pilot Yen Hsiang-sheng, 33, a lieutenant colonel who did his flight training at Luke Air Force Base in the United States.

Yen has intercepted Chinese H-6 bombers and J-11 fighters, and said he is confident of Taiwan’s defense forces.

“I believe that our performance can match the abilities of the mainland’s newest J-10 and J-11 fighters,” Yen said.

China has sent about 2,000 bomber patrols a year to the Taiwan Strait, Taiwan Defense Minister Yen Teh-fa told parliament in November.

President Tsai Ing-wen, re-elected in a landslide on Saturday after promising to stand up to China’s threats, has made strengthening Taiwan’s defenses a top priority, including boosting its domestic defense industry so it can make high-tech equipment like submarines.

Taiwan’s air force, though well trained, is dwarfed by that of China, which is adding stealth fighters and whose bombers have flown regular drills around the island since 2016, when Tsai first took office.

China has not so far flexed its military muscles in response to the vote, but state media has suggested it is an option.

The Chiayi F-16s fly regular patrols over the Taiwan Strait, sometimes skimming so low that they have to be washed when they return to remove the salt spray and prevent corrosion.

Due to Chinese pressure and Taiwan’s diplomatic isolation, the United States is the only major country that sells the island weapons, and is indeed bound by law to provide Taiwan with the means to defend itself.

Last year the United States approved an $8 billion (880 billion yen) sale of 66 new Lockheed Martin Corp F-16 fighters and 75 General Electric Co. engines, as well as other systems.

Taiwan is also upgrading its existing 144 F-16 A/B jets into the more advanced F-16V variant. That is expected to be complete by 2022. About 15 are already in service at Chiayi.