North Korea yesterday condemned a port visit by a US aircraft carrier to South Korea as a "reckless" act of provocation after proposals by Pyongyang to ease cross-border tensions. The USS George Washington arrived in the southern port of Busan on Friday for joint military exercises starting this week. A spokesman for the policy department of the North's National Defence Commission (NDC) said the visit was "little short of US 'gunboat diplomacy' in the last century" and "in defiance" of Pyongyang's overtures. "The US should properly understand that the more persistently it resorts to reckless nuclear blackmail and threat, the further [North Korea] will bolster its cutting-edge nuclear force for self-defence," the spokesman was quoted as saying by the North's official Korean Central News Agency (KCNA). He said the exercises, which were taking place after North Korea reached out recently, were an "open challenge" to its efforts. "Whenever there was a sign of improving the North-South relations and détente on the peninsula, the US resorted to sinister interference and obstructions," he said in reference to the upcoming drills. The George Washington is scheduled to take part in joint exercises with the South Korean navy from July 16-21 as part of annual military drills, Seoul's Yonhap news agency said. It will then participate in a search-and-rescue exercise with South Korean and Japanese maritime forces in waters off the southern island of Jeju for two days starting on July 21, it said. The NDC recently called for both the North and the South to halt all hostile military activities - a suggestion Seoul dismissed as "nonsensical" in the light of Pyongyang's nuclear-weapons programme. North Korea issued another call last Monday for a lowering of military tensions with South Korea, even as leader Kim Jong-un oversaw firing drills on an island near the sensitive maritime border. A government statement carried by KCNA said it was time to end "reckless hostility and confrontation" and called on Seoul to scrap its annual joint military drills with the United States. On Friday, South Korea agreed to hold working talks with North Korea on Pyongyang's decision to send a delegation of athletes and cheerleaders to the upcoming Asian Games in Incheon. The talks are ostensibly aimed at sorting out logistical matters such as how the North's delegation will travel to the South and where they will stay.