Taiwan held a major missile drill Tuesday just days after rival China unveiled an aircraft that uses stealth technology, but several misses spoiled the exercise.

Before an audience that included President Ma Ying-jeou, five out of 19 missiles failed to hit their targets at the Chiupeng military base in the island's south. A sixth found its target, but did not explode.

"It's within our predictions, but of course there's room for improvement," said air force Lieutenant General Pan Kung-hsiao, when asked to comment about the missiles that went astray.

Ma, however, was less forgiving, telling journalists that the military should get to the bottom of the failures.

"I'm not very satisfied," Ma said. "Some missiles missed the targets, and we need to review whether these errors were mechanical or human. We also need to hold more drills to boost military capabilities."

While one missile plunged almost directly into the nearby ocean, the others were near-misses, and some of them virtually scratched their targets but were still declared failures.

The missile drill at the normally tightly guarded base was the largest open to the media since Ma assumed power in 2008.

It was meant to signal Taiwan's defence capabilities to the island's own public just days after China unveiled the J-20, an aircraft that uses stealth technology to avoid radar detection, according to analysts.

"Taiwan wants to reassure its people at a time when China keeps developing advanced weapons such as the J-20," said Edward Chen, a political scientist at Tamkang University's Graduate Institute of American Studies.

The drill also came on the same day that China's President Hu Jintao left for a state visit to the United States, with Taiwan likely to be on the agenda.

On Monday, Ma told an American visitor -- Arthur Brooks, president of the American Enterprise Institute, a Washington-based think tank -- that he was "very concerned" about Hu's visit.

China and Taiwan have been governed separately since the end of a civil war in 1949, but Beijing considers the island part of its territory, and has never renounced the possible use of force to get it back.

Relations have improved since Ma took over as president in 2008 on a campaign promise to lift the island's economy through closer interaction with China.

However, underlying tensions remain, and analysts said the exercise was a signal from Ma that he wants Taiwan to maintain sufficient defensive capability while pressing for dialogue with China.

"Through the drill, Taipei is showing Washington it has the determination to defend itself," said Alexander Huang, a Taipei-based defence analyst.

"At the same time, it tells Beijing that it will go ahead with its arms build-up despite the reduced hostilities in the region."

The scenario played out in Tuesday's exercise left no doubt about where Taiwan sees its main, or only, military threat.

The drill simulated an attack by Chinese aircraft after two waves of ballistic missiles had hit the island, causing serious damage to military establishments.

"All the weapons tested today were defensive in nature," Ma said. "We don't seek wars, rather we want to prevent them from happening."

Among the weapon systems tested Tuesday were Taiwan's Tien Kung, or "Sky Bow" surface-to-air missiles, French-made Mica and Magic air-to-air missiles and US-made Hawk surface-to-air missiles.

Military authorities said the drill was launched only after they were certain that no Chinese spy ships were near the coastal missile base.