In March 2008, the U.S. Department of Defense released its annual Report to Congress on the Military Power of the People's Republic of China . According to the report, DOD officials estimate that the People's Liberation Army Navy currently operates 74 principal combatants, 57 attack submarines, 55 medium and heavy amphibious ships, and 49 coastal missile patrol craft. The report states that two Type 093 SSNs and one Type 094 SSBN may enter service in the near future. Ten Song -class (Type 039) conventionally powered submarines are already in service while newer Yuan-class boats are in full production and can be expected in service by 2010. The report also highlights that seven large surface warships have been built domestically since 2006, including two each of the Type 052C and Type 051C guided-missile destroyers and three Type 054A guided-missile frigates. These new combatants join a number of increasingly advanced warships, including four Russian-built Sovremennyy -class destroyers, the newest of which, number 139, is shown here shortly after entering service in 2006.