JIADONG, Taiwan — The F-16 screeched across the sky Wednesday before landing on a highway cut through pineapple fields in southwestern Taiwan to refuel quickly and take off again.

The Taiwanese military exercise envisioned a Chinese attack taking out the island’s main airfields, necessitating the use of rural roads as runways to carry on the fight.

War is not imminent, but as China has grown increasingly assertive in both the East China and South China Seas, Taiwan is stepping up its defense. Across the region, the United States and its allies are deepening military cooperation and strategizing over an effective response.

China, which claims Taiwan as part of its territory, flies fighter jets toward Taiwan on a regular basis in an effort to warn and intimidate the island’s air force. Last month, Chinese fighter jets, anti-submarine aircraft and combat ships conducted joint assault drills near Taiwan with China saying the exercise was necessary to safeguard its sovereignty.

U.S. President Joe Biden on Tuesday announced a meeting next week with key regional players that form the so-called “Quad” — India, Australia and Japan together with the U.S. — for in-person talks the White House said are meant to show the administration’s commitment to “promoting a free and open Indo-Pacific.”

Chinese Foreign Ministry spokesperson Zhao Lijian slammed the U.S. for “forming exclusive cliques” after the meeting was announced and countered that China was a “firm defender of regional peace and stability.”

“China’s development is a growing force for peace in the world and a boon to the prosperity and development of the region,” he said. “The countries concerned should abandon the outdated zero-sum mentality and narrow-minded geopolitical thinking.”

Japan, a U.S. ally that hosts the U.S. Navy’s 7th Fleet, has long moved cautiously with regard to China, an important trading partner. But it has recently become less reserved in the face of Beijing’s growing military activity and broad territorial claims in the western Pacific, including to a group of islands near Taiwan that Japan controls.

Masahisa Sato, a senior lawmaker of the governing Liberal Democratic Party and an expert on defense, told a recent forum on security in Asia that right now the U.S.-Japan alliance is focused largely on a response to a possible conflict stemming from the Korean Peninsula, and it needs to be broadened to consider what to do if there is a Chinese attack on Taiwan.

He noted that the Sakishima island group, which includes some of Okinawa’s remote islands, “is right next to Taiwan and is part of a same theater.”

“We should consider a Taiwan contingency as nearly equal to a Japan contingency,” Sato said.

All three candidates running on Sept. 29 to become Japan’s new leader are proposing hawkish policies toward China, though still acknowledging its importance as a trading partner.

Taro Kono, the minister in charge of vaccinations who is seen as a front runner, has said he will seek to establish a regional framework that adds to Japan’s alliance with the United States in countering China’s growing military activity.

In a joint statement after they met in April, outgoing Prime Minister Yoshihide Suga and Biden said they “recognize the importance of deterrence to maintain peace and stability in the region” and added that they “oppose any unilateral attempts to change the status quo in the East China Sea” and reiterated their “objections to China’s unlawful maritime claims and activities in the South China Sea.”

Underscoring its concerns, Japan’s Defense Ministry added a new section on Taiwan in its annual report released in July, saying the situation requires a “sense of crisis.” It says China’s military capability has become far greater than that of Taiwan and that Japan must pay attention to further increases on both sides.

Suga announced he will not run in the Sept. 29 Liberal Democratic Party leadership vote, which chooses a new party leader who will become Japan’s next prime minister.

Taiwan has stepped up purchases from the U.S. of weapons including missiles and aircraft over the past two years.

Taiwan’s defense ministry submitted a budget of $16.8 billion for the next year, a modest increase from last year’s $16.2 billion. Some of the funds would purchase 66 F-16V fighter jets, according to the semiofficial Central News Agency.

Many believe, however, that despite the bellicose rhetoric and drills like the Han Guang exercise on Wednesday, as well as the Chinese posturing, that open conflict is not on the horizon.

“This is a type of gray zone tactic — military intimidation,” said Ou Xifu, a researcher at the Institute for National Defense and Security Research in Taiwan. “This shouldn’t lead to war.”

Wu reported from Taipei and Yamaguchi from Tokyo. Associated Press researcher Yu Bing contributed to this report from Beijing.

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