unilateralist

adj

1. Supporting or advocating unilateralism

   “Yet he emerged as the driving force for the administration’s unilateralist policies.”

   “the US is hegemonic, unilateralist, dismissive of international law and the United Nations”

noun

1. A supporter of unilateralism.

   ““I am the last of the standing unilateralists,” Mr. Oren declared in a lecture in March at Georgetown University, where he was a visiting professor in Jewish studies until being named ambassador.”