The United States has never declared war on Yemen, and instead refers to the AUMF (Authorization to Use Military Force) resolution of 14 September 2001 to justify their intervention in Yemen, despite the fact that the Yemeni government is considered an ally and does not represent a threat to the US. The AUMF sets out measures to combat those with ties of any kind to the attacks of 11 September 2001. This has been interpreted to include all those that are considered to be “associated forces” of al-Qaeda, although this phrase does not appear in the resolution itself.