WASHINGTON, May 25 (AFP) - US Defense Secretary William Cohen has postponed plans for a trip to China next month because of the NATO air campaign against Yugoslavia, his spokesman said Tuesday, acknowledging that "it probably is not the easiest time to be visiting China." US-China relations were rocked earlier this month by the mistaken bombing of the Chinese embassy in Belgrade and suffered another blow Tuesday with the release of a congressional report that accused Beijing of widespread theft of US nuclear secrets. Cohen had tentative plans to visit China in June but decided to postpone "any trip until some later date," Pentagon spokesman Kenneth Bacon said. "I think the primary reason for that is that right now he feels that his place is here in Washington devoting as much time as possible to running the US participation in the air campaign in Kosovo, preparing for the peacekeeping force, et cetera," he said. "But also it probably is not the easiest time to visit China," he said. "China, as you know, has broken off military-to-military relations temporarily with the United States and he feels that it may be better to go later." Beijing suspended the military-to-military contacts with the Pentagon, as well as port calls by the US Navy to Hong Kong, after the Chinese embassy in Belgrade was struck May 7 during a NATO raid, killing three people. Washington apologized for the bombing, saying it was a mistake resulting from outdated maps and data bases. But China, whose official media suggested the attack was deliberate, has demanded a full investigation. In a report submitted to NATO Secretary General Javier Solana over the weekend, NATO commander General Wesley Clark blamed the faulty maps for the bombing and exonerated the pilot, a NATO official in Brussels said. In Washington, meanwhile, a long-awaited report by a congressional panel found that China stole classified information on every currently deployed warhead in the US arsenal in a decades-long espionage effort that focused on Department of Energy weapons laboratories. "Obviously, any successful espionage effort was disturbing and we devote a lot of resources to blocking espionage by a variety of countries," Bacon said. "We understand that it is part of national life. Espionage ... does occur." The Pentagon has taken steps to tightened security at its weapons laboratories, Bacon said. But he said Cohen remains "steadfastly committed to engagement with China as a long-term policy."  