The Strategic Airlift Capability is a multinational initiative aimed at providing participating nations with access to military strategic airlift. The ten NATO nations involved are Bulgaria, Estonia, Hungary, Lithuania, the Netherlands, Norway, Poland, Romania, Slovenia and the United States of America and the two Partnership-for-Peace (PfP) nations Finland and Sweden.
More about that here: https://www.nato.int/cps/en/natohq/topics_50107.htm
