US decisions on selling missile-defence technology depend in large measure on the actions that the Chinese themselves take

Admiral Dennis Blair

"There will be a point at which that missile build-up will threaten the sufficient defence of Taiwan which it is the United States' policy to maintain," Admiral Dennis Blair said during a six-day tour of China to meet defence officials.

"The decisions that the United States will make on selling missile-defence technology... depend in large measure on the actions that the Chinese themselves take with [their] missiles."

The Chinese Government has constantly urged the US to stop selling arms to Taiwan, which it considers a renegade province that must be reunited with China.

Both countries have raised the rhetoric on the contentious issue ahead of annual US-Taiwan arms talks, expected in April.

Missile defence system

Admiral Blair welcomed China's new willingness to talk about American plans to set up a multi-billion dollar missile defence shield system.

NMD will give the US early warning of attack

In the past, China has stridently opposed US plans for a National Missile Defence system (NMD) or a scaled-down "theatre" system in Asia, saying it could start a new global arms race.

On Wednesday, Sha Zukang, head of China's arms control department in the foreign ministry, said Beijing was willing to discuss the NMD.

But Mr Sha added that attempting to solve the problem of missile proliferation with NMD would be like "drinking poison in order to quench one's thirst".

He also said the presence in Asia of a smaller shield would damage the region's stability.

Washington says the missile shield is necessary to protect the United States from missile attacks by hostile states such as North Korea and Iraq.

But the plans have drawn strong opposition from many countries, including Russia.