Chinese and U.S. soldiers participate in the counter-piracy exercise on the missile destroyer "Harbin" of Chinese navy in the Gulf of Aden, Aug. 25, 2013. The Chinese and U.S. navies conducted a joint counter-piracy exercise in the Gulf of Aden on Saturday and Sunday.(Xinhua/Rao Rao)

Chinese and U.S. soldiers communicate with each other during the counter-piracy exercise in the Gulf of Aden, Aug. 25, 2013. The Chinese and U.S. navies conducted a joint counter-piracy exercise in the Gulf of Aden on Saturday and Sunday.(Xinhua/Rao Rao)

Chinese and U.S. soldiers participate in the counter-piracy exercise in the Gulf of Aden, Aug. 25, 2013. The Chinese and U.S. navies conducted a joint counter-piracy exercise in the Gulf of Aden on Saturday and Sunday.(Xinhua/Rao Rao)

Photo taken on Aug. 25, 2013 shows the warships participating in a joint counter-piracy exercise in the Gulf of Aden. The Chinese and U.S. navies conducted a joint counter-piracy exercise in the Gulf of Aden on Saturday and Sunday. (Xinhua/Rao Rao)

A soldier participates in the counter-piracy exercise on the missile destroyer "Harbin" of Chinese navy in the Gulf of Aden, Aug. 25, 2013. The Chinese and U.S. navies conducted a joint counter-piracy exercise in the Gulf of Aden on Saturday and Sunday.(Xinhua/Rao Rao)

The missile destroyer "Harbin" of Chinese navy participates in the counter-piracy exercise in the Gulf of Aden, Aug. 25, 2013. The Chinese and U.S. navies conducted a joint counter-piracy exercise in the Gulf of Aden on Saturday and Sunday.(Xinhua/Rao Rao)

A helicopter of the U.S. navy lands on the missile destroyer "Harbin" of Chinese navy during the counter-piracy exercise in the Gulf of Aden, Aug. 25, 2013. The Chinese and U.S. navies conducted a joint counter-piracy exercise in the Gulf of Aden on Saturday and Sunday.(Xinhua/Rao Rao)