A team of officials from the United States, China and Russia headed Wednesday to North Korea's main nuclear facilities to study how to disable them. Allowing the visit is the latest positive step by North Korea toward disarming, creating enough goodwill between Washington and Pyongyang that the U.S. ambassador to South Korea suggested Wednesday that U.S. President George W. Bush and North Korean leader Kim Jong Il could hold a summit if North Korea totally disarms. «I think that it might be possible before the end of President Bush's term if North Korea makes the right decisions and is ready to go all the way, not just disablement but full denuclearization,» Ambassador Alexander Vershbow told a security forum in Seoul in comments confirmed by the U.S. Embassy, the Associated Press reported.