SEOUL, Dec 2 (Reuters) - North Korea"s missile and weapons developments are increasingly destabilising for regional security, U.S. Defence Secretary Lloyd Austin said on Thursday after talks with his South Korean counterpart in Seoul. The United States calls on the North to engage in dialogue, Austin told a news conference, saying diplomacy is the best approach to pursue with North Korea, backed up by a credible deterrent. Austin and U.S. Army General Mark Milley, chairman of the Joint Chiefs of Staff, held annual military talks with South Korean officials, covering an update to operational planning for a potential conflict with North Korea. The United States has pledged to maintain the current level of U.S. troops in South Korea which stands at 28,500, South Korea"s Defence Minister Suh Wook said after talks Austin. Suh also said the two sides made progress on meeting conditions for the transfer of wartime command control of their combined forces to South Korea.