Sentence:  The United States was <WSD>engaged</WSD> in a military attack on a peaceful , orderly people governed by a regime that had proved itself the most pro-Western and anti-Communist within any of the new nations - the only place in Africa , moreover , where a productive relationship between whites and blacks had apparently been achieved . 
Meaning of the word marked with <WSD> tags:  carry out or participate in an activity; be involved in