Chinese and US naval vessels have conducted their first joint anti-piracy exercise in the Gulf of Aden, officials said Tuesday, citing the drill as a sign of improving security ties. The five-hour drill featured a Chinese missile frigate, the Yi Yang, and American guided missile destroyer the USS Winston S. Churchill, the US Navy and Chinese state media said. In the exercise the US destroyer played the part of a vessel taken over by pirates, while a joint American-Chinese team boarded the ship to “rescue” the crew, the US Navy’s Fifth Fleet said in a statement. “Executing the boarding side-by-side as a combined US-Chinese team, the team successfully searched the vessel and provided assistance to the role-playing mariners,” it said. US Defence Secretary Leon Panetta, on a three-day visit to China, praised the joint exercise as evidence that military ties between the two powers were advancing.