CSL meaning in Military and Defence ?

A cooperative security location (CSL) is a U.S. military term for facilities used for regional training in counterterrorism and interdiction of drug trafficking, and also to provide contingency access to continental areas.

"A CSL is a host-nation facility with little or no permanent U.S. personnel presence, which may contain pre-positioned equipment and/or logistical arrangements and serve both for security cooperation activities and contingency access." These sites were established as the Pentagon began to address regional threats primarily in Africa and Latin America following its 2004 global posture review. They are sometimes referred to as "lily pads". The establishment of such bases accelerated under the Obama administration, especially with the pivot to the Asia-Pacific region and increased operations in Africa.

A CSL is differentiated from a forward operating site (FOS) with a small permanent force or contractor personnel, or a main operating base (MOB), with a large force and a well-defended site.

Canada has established operational support hubs that operate in a similar fashion and can be reached by Canada's fleet of C-17 cargo aircraft.