T AIWAN “MUST and will” be reunited with the mainland, declared Xi Jinping, China’s president, on January 2nd. Chinese leaders have been saying such things since the retreating Nationalists separated the island from the rest of the country after losing the civil war to the Communists in 1949. But Mr Xi has done more than just talk: he has sent bombers and warships to circle the island, held live-fire drills in the narrow Taiwan Strait and, Taiwanese generals say, instructed the People’s Liberation Army ( PLA ) to be capable of seizing Taiwan by force by next year. Back in 1996, the most recent cross-strait crisis, China’s military spending was barely twice Taiwan’s. Now it is 15 times greater. That has left Taiwanese leaders rushing to rethink their defences.

Taiwan already does a great deal to make itself indigestible to invaders. The island is “honeycombed with bunkers”, says Ian Easton of the Project 2049 Institute, an American think-tank. Tanks are hidden away in bustling neighbourhoods of Taipei. The Sun Yat-sen Memorial Highway Number One was built to handle not only rush-hour traffic, but also ten-tonne fighter jets, since the island’s airfields would quickly be destroyed by Chinese missiles should war break out.

America, Taiwan’s closest military ally, has urged the island to move further towards a “porcupine strategy”. It wants Taiwan to acquire smaller, cheaper and more mobile weapons that could wear down Chinese forces close to Taiwan’s shores, in the place of big, lumbering and expensive kit such as warplanes and battleships, which are better suited to projecting firepower onto China’s mainland.

Taiwanese planners have taken note. In 2017 the country’s top military officer launched the “Overall Defence Concept”. That strategy, endorsed by Tsai Ing-wen, the president, embraces the porcupine ethos. One priority is intelligent sea mines, which can scoot around and so evade sweeping. Some are more advanced than anything in America’s arsenal. Another focus is unmanned platforms, such as remote-controlled sentry guns to guard outlying islands and armed drones to patrol the coastline. Third is an emphasis on missiles. Taiwan is churning out Hsiung Feng cruise missiles by the hundreds. These can be placed not only on small, zippy speedboats rather than bulky destroyers, but also in unmarked lorries. Such rocket-laden vehicles are hidden “in places you cannot imagine”, says one official, and could continue to operate from anywhere on the road network long after invaders had obliterated Taiwan’s fighter jets. Better yet, they are far cheaper than warplanes.

Yet not everyone is willing to jettison traditional ways of war. The new defence policy appeals to the president and her staff not only for its military virtues, but also because it favours the smaller systems that Taiwan can build itself. But the top brass has reasons beyond vanity to defend their shiny objects.

They concede that heavy tanks, big ships and fancy warplanes may not survive a head-to-head conflict with China. But they act as a deterrent and boost morale. Missiles cannot fend off prowling Chinese bombers nor speedboats patrol stormy oceans. “Parades are a form of deterrence, certainly in Asia,” notes Drew Thompson, who used to help shape policy on Taiwan at America’s Department of Defence. “Big-ticket items parade well.”

They also let Taiwan take the fight to China. Taiwan’s American-made frigates would eventually be blown out of the water, but not before their potent torpedoes might inflict serious damage on Chinese ships. That would not only boost the morale of islanders facing a hailstorm of missiles, it might also induce caution in Mr Xi.

The problem is that showcase weapons are expensive. Even domestically built submarines—Taiwan hopes to make eight—cost more than $1bn apiece; the entire annual defence budget is just $11bn. Money is even tighter because Taiwan is scrapping conscription and shifting to an all-volunteer force. And since salaried soldiers are pricier, their numbers are fewer. Taiwan’s armed forces have shed more than 150,000 people since China’s cross-strait muscle-flexing in 1996, leaving 215,000. The country’s reserve force, its second line of defence, will also shrink with every passing year. Even so, any return to compulsory enlistment would be electoral suicide, politicians say.

American arms, even big, expensive ones at odds with the porcupine philosophy, also serve a diplomatic purpose. America’s involvement in a war could be the difference between Taiwan’s survival and extinction. Just eight American submarines could sink 40% of China’s amphibious fleet in the first week of fighting, according to computer simulations by the RAND Corporation, a think-tank.

Although America does not have diplomatic relations with Taiwan, it maintains close ties. Some 3,500-4,000 Pentagon officials travel to Taiwan every year, an average of more than ten per day. Arms sales have totalled more than $15bn since 2010. The relationship is deepening in some respects. Arms transfers were previously bundled into big packages that reliably aroused Chinese anger; they are now growing more routine.

The administration of Donald Trump is stacked with senior officials who know Taiwan well and sympathise with its plight. Mr Trump delighted Taiwan’s leaders by holding a taboo-busting phone call with Ms Tsai when he was president-elect. Last year he also signed the Taiwan Travel Act, which encourages senior American officials to visit the island and vice versa. If arms sales help bolster America’s commitment to Taiwan, so much the better.

Though Mr Xi clearly feels obliged to continue to hound Taiwan about reunification, he has thus far avoided laying down a firm timeline. The relatively slow growth of China’s amphibious fleet casts doubt on the idea that the PLA is working flat out to be ready to invade. Nor has it been conducting big amphibious exercises. There is still time for Taiwan to sharpen its quills.

Correction (January 24th 2019): The original version of this article said that an average of more than 100 Pentagon officials travelled to Taiwan each day. Our maths let us down. Daily visitors from the Pentagon number “more than ten”. This has been corrected.