US Democratic Senator Chris Murphy believes the killing of Iranian general Qasem Soleimani could lead to war.

"Soleimani was an enemy of the United States. That’s not a question. The question is this - as reports suggest, did America just assassinate, without any congressional authorization, the second most powerful person in Iran, knowingly setting off a potential massive regional war?" Murphy tweeted. "The justification for the assasination is to “deter future Iranian attacks”. One reason we don’t generally assasinate foreign political officials is the belief that such action will get more, not less, Americans killed. That should be our real, pressing and grave worry tonight."