Although much attention has been on Speaker Nancy Pelosi’s visit to Taiwan, the real potential for a military showdown comes now that she has left.

China’s military has said it will conduct a series of live-fire drills beginning on Thursday. A post on Chinese state media offered coordinates for five swathes of the sea surrounding Taiwan, three of which overlap with areas that Taiwan says are a part of its territorial waters.

The drills, assuming that they go forward, would mark a direct challenge to what Taiwan defines as its coastline. They would also strike at the heart of a decades-long disagreement in which China claims sovereignty over Taiwan, a self-ruled island with its own democratically elected government and military.

A New York Times map of the planned drills shows how in some places they will occur within 10 miles of Taiwan’s coast, well past areas that previous live-fire drills have targeted and within areas, Taiwan designates as its territorial waters. Two of the regions where China’s military will shoot weapons, likely missiles and artillery, are inside what Taiwan calls its marine border. In total, the five zones surround the island and mark a clear escalation from previous Chinese exercises.

In its warning, China’s military called for all boats and aeroplanes to avoid the areas it identified for three days. For Taiwan, and the US military, a key question will be whether they obey the orders or test China’s resolve to carry out the tests by sending boats and planes into those zones.

The standoff is reminiscent of an incident in 1995 and 1996 called the Third Taiwan Strait Crisis. Back then, China fired live ammunition and missiles into the waters around Taiwan to signal its anger over a trip by Taiwan’s then-President, Li Teng-hui, to the US. The US then sent two aircraft carrier groups to the area and sailed one through the Taiwan Strait.

The new live-fire drills will occur in areas closer to the island than those in 1995and 1996, presenting a conundrum to Taiwan and the US. If China takes action, it must decide whether to offer a show of force similar to the earlier crisis.

Much has changed since then. China’s military is more powerful and more emboldened under Xi Jinping. This summer, Chinese officials also strongly asserted that no part of the Taiwan Strait could be considered international waters, meaning they might move to intercept and block US warships sailing through the area, one of the busiest shipping lanes in the world.

China has wasted little time in signalling that it is serious. On Wednesday its state broadcaster released images from preparatory drills in the area indicating Chinese forces were in the north, southwest and southeast of Taiwan to practice sea assaults and land strikes, aerial combat and “joint containment”.

Also on Wednesday, Taiwan’s military sought to hold the line, while signalling that it did not wish to escalate the situation. Calling the drills a blockade, it said the exercises had intruded into Taiwan’sterritorial waters.

New York Times News Service