The Vietnamese government Monday gave a boost to the search for missing US servicemen from the Vietnam War, telling visiting US Defense Secretary Leon Panetta they would open three previously closed sites to permit excavation for remains. Vietnamese Defense Minister Phung Quang Thanh told Panetta of the decision during a meeting at his ministry, where they discussed the US strategic shift toward the Asia-Pacific region, and its implications for their growing military ties. The United States is looking to expand military ties with Vietnam after they signed last year a memorandum of understanding on defense cooperation. On Sunday, Panetta became the most senior US official since the end of the Vietnam War to visit Cam Ranh Bay in central Vietnam, a US logistics hub during the conflict. He visited a US Navy cargo ship that was undergoing repairs at the Vietnamese port. The Vietnamese decision to lift restrictions on three sites will help the Joint Prisoners of War, Missing in Action Accounting Command's (JPAC) search for four missing servicemen. Ron Ward, a casualty resolution specialist at JPAC, said Vietnam occasionally restricted access to suspected casualty sites. One place where restrictions were lifted on Monday was the suspected 1967 crash site of an F-4C Phantom in Quang Binh province in central Vietnam just north of the former demilitarized zone, he said. “We located the site in 2008 but soon thereafter the Vietnamese informed us that site was restricted for some reason,” he said. “So we're pleased to find out that today ... the restriction on that site has been lifted.” The second site where restrictions were lifted was the scene of a 1968 firefight in Kon Tum province near the borders with Laos and Cambodia, and the final site was the scene of a crash of a Marine Corps F-4J in Quang Tri province. Panetta's visit is part of a week-long trip to the Asia-Pacific region to explain Washington's new military strategy, which will see 60 percent of US warships deployed in the region by 2020, compared to 50 percent now.