TAIPEI, Taiwan - Residents practiced fleeing their apartment buildings and flocking to underground parking garages on Thursday afternoon, as air raid sirens blared across Taiwan’s capital region, home to 7 million people. In the city’s main stadium - which usually hosts pop concerts and basketball games - army reservists in red bibs simulated distributing rice, cooking oil and other emergency rations. Classrooms at an elementary school became mock operating theaters and first aid stations.

Across this city, everyone from office workers and retirees to firefighters and doctors practiced what to do if one day China were to invade, holding “whole of society” drills that were unprecedented in scale and complexity, according to Taiwanese officials and analysts.

“In the past, it was more about evacuation,” said Lee Juwen, a local government employee in Songshan District, as she took shelter from a mock missile attack. “This year is especially about what is really needed if a war breaks out. When something happens, we will know immediately what to do.”

Taiwan has been preparing for a Chinese assault for decades. The Chinese Communist Party has never ruled Taiwan, but it claims the self-governing island democracy as part of its territory and regularly threatens to use force to bring it under control. But this year’s Han Kuang military exercises have lasted 10 days - double last year’s length - and called up 22,000 reservists, up from only 14,500 last year.

They were also more realistic, going beyond scripted role-playing to include drills on what might happen before - and after - Chinese troops storm Taiwan’s shores. And they encouraged more public participation, with civil defense and emergency response measures combined into “urban resilience” drills held across the island this week.

The emphasis on preparing everyone for Chinese attack is one of Taiwanese President Lai Ching-te’s signature policies and a key part of his effort to address concerns in Washington that slow-going defense reforms are leaving the island vulnerable to Chinese aggression.

“This is President Lai’s most significant undertaking to date,” said Mark Montgomery, a retired rear admiral in the U.S. Navy now at the Foundation for Defense of Democracies, a think tank in Washington.

The idea is to strengthen institutions and train civilians to resist Chinese campaigns that might try to compel Taiwan to surrender without a fight. China could cut off the island’s access to liquid natural gas, sever an undersea communications cable or launch cyberattacks.

“This is the most likely scenario, and it’s the one where [Chinese leader Xi Jinping] could possibly win Taiwan without firing a weapon,” Montgomery said. “It is something that Taiwan has to work on diligently … so that the public never loses faith in the government.”

Lai also needs to convince the United States that he is making progress. Although President Donald Trump has been preoccupied with conflicts in Ukraine and the Middle East, many in his administration consider deterring China from taking Taiwan to be the top priority for the U.S. military.

In an internal Pentagon memo in March, Defense Secretary Pete Hegseth indicated that denying a Chinese takeover of Taiwan was more important for the U.S. military than preparing for a potential war with Russia. The Chinese military threat to Taiwan is real and “could be imminent,” Hegseth warned publicly in May.

But officials have also urged Taipei to do more to meet the Chinese threat. Elbridge A. Colby, undersecretary of defense for policy, said at his confirmation hearing in March that Taiwan’s defense budget should be 10 percent of its gross domestic product - four times current spending - and warned that it was not fair to ask Americans “to suffer if our allies are not pulling their weight.”

The U.S. maintains a policy of “strategic ambiguity” over when it might intervene to defend Taiwan from Chinese attack. But current and former U.S. service members have in recent years worked increasingly closely with Taipei on defense reforms and training with U.S.-made weapons.

“When exercises were designed in the past, they got to the People’s Liberation Army landing on the beach, then the drills were over,” said Yang Tai-yuan, a retired colonel in the Taiwanese military now at the Research Project on China’s Defense Affairs, a Taipei think tank.

Urban warfare and preparation for a drawn-out conflict were recently added, in no small part thanks to advice from the American military trainers, Yang said.

Washington had long been concerned that Taiwan’s Han Kuang drills were not realistic enough and didn’t sufficiently test the military, said Lauren Dickey, a former senior adviser for Taiwan policy in the U.S. Department of Defense, now affiliated with the Center for Strategic and International Studies, a Washington think tank.

“The fact that they are accounting for other elements of what conflict could look like, that’s a net positive and a huge sign of progress,” said Dickey.

China’s escalating pressure campaign has intensified American concerns about Taiwan’s lagging defense reforms. Under President Joe Biden, tensions over Taiwan repeatedly thwarted efforts to stabilize U.S.-China ties after Russia’s invasion of Ukraine sharpened fears that Taiwan could be next. Soon after, CIA Director William J. Burns warned that Xi had instructed his military to be capable of seizing Taiwan by 2027.

While U.S. officials have since downplayed the possibility of imminent attack, they continue to warn that Taiwan must be prepared for the worst.

The Lai administration has tried to show it is taking those warnings seriously. Its Defense Ministry described this month’s drills as designed with a potential 2027 Chinese invasion in mind.

The simulation began with Chinese “gray zone” operations - acts of sabotage or aggression that stop short of outright conflict - that Beijing could use to sow panic ahead of a full-scale invasion. These included cyberattacks and misinformation campaigns, and an exercise based on Chinese Coast Guard ships entering Taiwan’s restricted waters.

Later, the focus shifted to urban warfare. In nighttime drills, soldiers rushed rocket launchers through the subway system. Military police blockaded one of the main bridges into Taipei using buses and barbed wire barricades. Police and fire fighters practiced getting people to shelter, halting traffic and distributing emergency supplies.

The idea was to teach “every city and local government what to do when faced with war,” said Shen Ming-Shih, an analyst at the Institute for National Defense and Security Research, a Taiwanese think tank.

Taiwan also practiced repelling an amphibious invasion using newly arrived American weaponry, including the truck-based High Mobility Artillery Rocket System (HIMARS) missiles defense system that has been a cornerstone of Ukraine’s defenses. Lai watched on Thursday as four U.S.-made Abrams tanks - delivered late last year after months of delays - practiced hitting targets shaped like Chinese tanks.

Seeing weapons from Taiwan’s main security backer in action “is also helpful for raising the will to resist across the whole of society,” Shen said.

Lai has repeatedly warned that Taiwan needs to contend not just with a Chinese attack, but with a “defeatist attitude” when faced with Chinese propaganda intended to convince Taiwanese that resistance is futile.

Faced with daily threats and coercion, “there is no other choice but to be prepared,” Lai said in a speech Thursday. “We must actively and comprehensively promote whole-of-society defense resilience, so that everyone understands that national defense is everyone’s responsibility.”

Beijing has responded angrily to Lai’s defense reforms and his forceful rejection of China’s territorial claims. The Chinese military has repeatedly launched large-scale military drills around Taiwan since he took office and blamed Lai personally for “poisoning” the minds of Taiwanese people.

China’s Taiwan Affairs Office dismissed this month’s drills as “military theatrics” and accused Lai of “forcibly tying Taiwan residents to the chariot of separatism.”

But even Chinese analysts acknowledged that this year’s Han Kuang drills showed Lai has a clear understanding of what is required to resist forced unification. Taiwan is readying for a “last-ditch fight” that would keep China engaged for long enough that “external forces” - the U.S. and its allies - could come to their aid, Zhang Junshe, a Chinese military commentator, told state-run newspaper the Global Times.

“A big problem is that Taiwanese society is already numb to this Chinese military harassment,” said Chen Shih-min, an associate professor of political science at National Taiwan University.

“Before people would often say, if China attacks Taiwan, it can take control in three days - or in a week or a month,” Chen said. “The whole world and all Taiwanese people must clearly understand that as soon as China attacks or invades, this government will without a doubt fight to the last.”