China has launched a new round of military drills near Taiwan, having previously announced they were ending on Sunday. The People’s Liberation Army’s Eastern Theatre Command said it was ‘continuing joint training under real war conditions, focused on organising joint anti-submarine warfare and naval strikes’. A social media account of the nationalist tabloid Global Times said exercises around Taiwan might continue, since the summer is a popular drill season for the PLA.

Taiwan said it was closely monitoring the exercises, but that so far Monday no Chinese ships or aircraft had entered its territorial waters. Joseph Wu, Taiwan’s foreign minister, said in an interview with the American broadcaster CNN that the island was not scared, even though the threat from China was ‘more serious than ever’. He vowed to stand firm to protect Taiwan’s freedom and democracy.

The US nuclear-powered supercarrier, the USS Ronald Reagan and its battlegroup are in the area. They were last reported to be in Philippine Sea, east of Taiwan and south of Japan. The US has so far kept a low profile during the drills, monitoring the Chinese military’s ability to undertake joint exercises between its various component parts – crucial to modern warfare and to any attempt to take Taiwan by force. But if the tempo of the PLA’s drills continue, Washington will come under growing pressure to make its presence felt to reassure jittery allies that is has not ceded control of the seas to the PLA.

Monday’s resumption of exercises follow four days of drills around Taiwan, which were the largest and most ambitious the Chinese military has ever held in the area. The PLA focussed on six zones, which effectively surrounded Taiwan, restricting access to aircraft and ships. They involved the army, air force, navy, the rocket force and support forces. They were accompanied by cyber-attacks on Taiwanese government web sites, and at one point ballistic missiles were fired high over the island.

Chinese ships and aircraft repeatedly crossed the median line in the Taiwan Strait, a sort of unofficial border in place since the 1950s, and which both sides have usually respected. Taiwan said that yesterday ten warships each from China and Taiwan were playing cat and mouse, manoeuvering at close quarters in the Strait, close to the line.

The drills followed a visit to Taipei last week by House of Representatives speaker Nancy Pelosi. Chinese analysts have likened the drills to a noose around the island, which it claims as its own, a practice run for a blockade. Though it fell well short of what would be needed for an invasion, which most analysts agree would be extremely challenging and require as many as two million troops.

It is best seen as an exercise in intimidation, and Monday’s drills suggest China plans to continue a high level of military activity, taking in a broader area. It has already announced exercises to start Saturday in the Yellow Sea, which is located between China and the Korean peninsula, and drills are underway in the Bohai Sae, north of the Yellow Sea.