Pakistan, Afghanistan, and Tajikistan have joined China in a military alliance aimed at countering Islamist militancy, officials said.
Military leaders from the four nations gathered August 4 in the northwestern Chinese region of Xinjiang to announce the alliance, the Pakistani Army said.
Known as the Quadrilateral Cooperation and Coordination Mechanism, the alliance is meant to bring together member states in areas of counter-terrorism and intelligence, the army said.
Pakistan and Afghanistan, both already U.S. allies in the war on terror, have faced violence from Islamist militant groups including al-Qaeda and the Taliban for more than a decade.
Tajikistan has been the victim of its own Islamist militants. China has been battling an ethnic minority group of Islamist militants in its Muslim-dominant, oil-rich region of Xinjiang near the country's border with Pakistan.
China is also working with Pakistan and the United States to broker so far fruitless peace talks to end a Taliban insurgency that has raged for 15 years in Afghanistan.
U.S. State Department spokesman Mark Toner said Washington welcomes the new alliance as a "positive" for the region.
"There's a lot of work to be done," he said.