In February 2011, the turbulent situation in Libya posed grave security threats to Chinese institutions, enterprises and nationals in that country. The Chinese government organized the largest overseas evacuation since the founding of the PRC, and 35,860 Chinese nationals were taken home. The PLA contributed ships and aircraft to the effort. The Chinese Navy' s frigate Xuzhou, on escort mission in the Gulf of Aden and waters off Somalia at that time, sailed to the waters off Libya and provided support for ships evacuating Chinese nationals stranded there. The PLAAF sent four aircraft at short notice, flew 40 sorties, evacuated 1,655 people (including 240 Nepalese) from Libya to Sudan, and took 287 Chinese nationals from Sudan back home.