China has been regularly sending warplanes into Taiwan air defence zone

Thirteen Chinese military aircraft entered Taiwan's air defence identification zone (ADIZ) on Friday.

This came on the day Nicaragua severed ties with Taiwan and established diplomatic relations with China.

The 13 Chinese planes entered Taiwan's southwestern ADIZ, with a sortie of two H-6 bombers and a Y-8 electronic warfare plane breaking off and intruding deep into the south-eastern ADIZ.

The other 10 aircraft were a Y-8 anti-submarine warfare plane, a KJ-500 third-generation airborne early warning and control (AEW&C) plane, and six Shenyang J-16 and two Chengdu J-10 fighter jets, Focus Taiwan reported citing Taiwan's defence ministry.

In response, Taiwan scrambled a combat air patrol, sent radio warnings, and deployed air defence missile systems to track the Chinese military fleet, the MND said.

China has been regularly sending warplanes into Taiwan air defence zone.

Taiwan's defence ministry has been publishing information about such flights since Sept. 17 last year, amid a growing incidence of intrusions into its ADIZ by Chinese military planes.

Air defence identification zones are early warning systems that help countries detect incursions into their airspace.

Any aircraft entering such an area is supposed to report its route and purpose to the "host" nation, though the zones are classified as international airspace and pilots are not legally bound to make such a notification.

Since mid-September of last year, Beijing has stepped up its grey-zone tactics by regularly sending planes into Taiwan's ADIZ, with most instances occurring in the southwest corner of the zone and usually consisting of one to three slow-flying turboprop planes.

Beijing claims full sovereignty over Taiwan, a democracy of almost 24 million people located off the south-eastern coast of mainland China, despite the fact that the two sides have been governed separately for more than seven decades.

Taipei, on the other hand, has countered the Chinese aggression by increasing strategic ties with democracies including the US, which has been repeatedly opposed by Beijing. China has threatened that "Taiwan's independence" means war.