The United States and China have signed a maritime safety agreement designed to prevent accidental clashes between their navies. The agreement came during a visit to Beijing by the US Defence Secretary, William Cohen. As part of a drive for greater openness and contact between the two military establishments, Mr Cohen also toured an underground air defence base. From Beijing, Carrie Gracie reports:

Foreigners are not normally welcome at China's top secret underground regional command centre on the outskirts of the capital but the American Defence Secretary was allowed in today, along with 14 senior officials, including the commander of US forces in the Asia Pacific region. US officials described the visit as a breakthrough, a concrete sign that China's People's Liberation Army is honouring its promise to strive for greater co-operation and openness with the US military.

From the underground base Mr Cohen went on to meet the Chinese Defence Minister, Chi Hao Tian, for the signing of a bilateral maritime agreement. The agreement is designed to increase naval contacts and to avoid accidental clashes between warships. The urgent need for such a pact was demonstrated two years ago during a stand-off between the two navies near the coast of Taiwan.

At today's signing ceremony, the American Defence Secretary said the agreement was a symbol of the maturing relationship between the two militaries. But the marked thaw in US/China military relations hasn't removed all problems at a stroke and during the talks between the Defence Ministers Mr Cohen raised American concerns over Chinese missile sales to Iran.