BEIJING (AP) — China on Wednesday reaffirmed its threat to use military force to bring self-governing Taiwan under its control, amid threatening Chinese military exercises that have raised tensions between the sides to their highest level in years.

The lengthy policy statement issued by the Cabinet’s Taiwan Affairs Office and its news department followed almost a week of missile firings and incursions into Taiwanese waters and airspace by Chinese warships and air force planes.

The actions have disrupted flights and shipping in a region crucial to global supply chains, prompting strong condemnation from the United States (US), Japan and others.

An English-language version of the Chinese statement said Beijing would “work with the greatest sincerity and exert our utmost efforts to achieve peaceful reunification.”

“But we will not renounce the use of force, and we reserve the option of taking all necessary measures. This is to guard against external interference and all separatist activities,” the statement said.

“We will always be ready to respond with the use of force or other necessary means to interference by external forces or radical action by separatist elements. Our ultimate goal is to ensure the prospects of China’s peaceful reunification and advance this process,” it said.

China says the threatening moves were prompted by a visit to Taiwan last week by US House Speaker Nancy Pelosi, but Taiwan says such visits are routine and that China used that merely as a pretext to up its threats.

In an additional response to Pelosi’s visit, China said it was cutting off dialogue on issues from maritime security to climate change with the US, Taiwan’s chief military and political backer.

Taiwan’s foreign minister warned Tuesday that the Chinese military drills reflect ambitions to control large swaths of the western Pacific, while Taipei conducted its own exercises to underscore its readiness to defend itself.

Beijing’s strategy would include controlling the East and South China seas via the Taiwan Strait and imposing a blockade to prevent the US and its allies from aiding Taiwan in the event of an attack, Joseph Wu told a news conference in Taipei.

Beijing extended the ongoing exercises without announcing when they would end, although they appear to have run their course for the time being.

China’s Defence Ministry and its Eastern Theatre Command both issued statements saying the exercises had achieved their targets of sending a warning to those favouring Taiwan’s formal independence and their foreign backers.

Taiwan President Tsai Ing-wen and her Democratic Progressive Party administration are “pushing Taiwan into the abyss of disaster and sooner or later will be nailed to the pillar of historical shame!” Defence Ministry spokesperson Col. Tan Kefei was quoted as saying in a statement posted to the ministry’s website.

Troops taking part in the exercises had “effectively tested integrated joint combat capabilities,” the Eastern Theatre Command said on its Twitter-like Weixin microblog.

“The theatre troops will monitor changes in the situation in the Taiwan Strait, continue to conduct military training and preparations, organise regular combat readiness patrols in the Taiwan Strait, and resolutely defend national sovereignty and territorial integrity,” spokesperson Col. Shi Yi was quoted as saying.

Taiwan split with the mainland amid civil war in 1949 and the island’s 23 million people overwhelmingly oppose political unification with China, while preferring to maintain close economic links and the status quo of de-facto independence.

Through its manoeuvres, China has pushed closer to Taiwan’s borders and may be seeking to establish a new normal in which it could eventually control access to the island’s ports and airspace.

Along with lobbing missiles into the Taiwan Strait, the nearly week-long drills saw Chinese ships and planes crossing the centerline in the strait that has long been seen as a buffer against outright conflict.

The US, Taipei’s main backer, has also shown itself to be willing to face down China’s threats. Washington has no formal diplomatic ties with Taiwan in deference to Beijing, but is legally bound to ensure the island can defend itself and to treat all threats against it as matters of grave concern.

That leaves open the question of whether Washington would dispatch forces if China attacked Taiwan. US President Joe Biden has said repeatedly the U.S. is bound to do so — but staff members have quickly walked back those comments.

Beyond the geopolitical risks, an extended crisis in the Taiwan Strait — a significant thoroughfare for global trade — could have major implications for international supply chains at a time when the world is already facing disruptions and uncertainty in the wake of the coronavirus pandemic and the war in Ukraine.

In particular, Taiwan is a crucial provider of computer chips for the global economy, including China’s high-tech sectors.

In response to the drills, Taiwan has put its forces on alert, but has so far refrained from taking active countermeasures.

On Tuesday, its military held live-fire artillery drills in Pingtung County on its southeastern coast.

Australia’s recent change of government was a chance to “reset” its troubled relationship with China, but the new administration must “handle the Taiwan question with caution,” a Chinese envoy said Wednesday.

China has brushed aside foreign criticism of its actions, and its ambassador to Australia said Wednesday he was “surprised” that Australia had signed a statement with the United States and Japan that condemned China’s firing of missiles into Japanese waters in response to Pelosi’s visit.

Xiao Qian told the National Press Club China wanted to resolve the situation peacefully, but “we can never rule out the option to use other means.”

“So when necessary, when compelled, we are ready to use all necessary means,” Xiao said. “As to what does it mean by ‘all necessary means?’ You can use your imagination.”