Sen. Richard Blumenthal is expressing concern about "potential escalation that could lead to war."

"No one should be mourning Qassim Suleimani," said Blumenthal. "He was a bad actor and an enemy of America with American blood on his hands. But now my hope is we can avoid war and my fear is that the administration may be stumbling into growing military confrontation with a strategy, without informing Congress, without involving our allies."

Blumenthal says the airstrike could lead to "the most consequential military confrontation in decades."

President Donald Trump ordered the strike in Baghdad that killed the top Iranian general last week. Iran has since vowed "harsh retaliation."

READ MORE: Iran abandons nuclear limits, Iraq's parliament votes to expel US troops after strike on general