Sen. Lindsey Graham just tweeted that US retaliation for Iran's overnight missile strikes "is not necessary" right now, marking a dramatic shift in tone from his comments last night.

"In my view, retaliation for the sake of retaliation is not necessary at this time," Graham tweeted. "What is necessary is to lay out our strategic objectives regarding Iran in a simple and firm fashion."

Graham, one of President Trump's top Senate allies, last night called the attack an "act of war."

Here's what he said yesterday:

"The missiles were launched from Iran at targets inside of Iraq housing US military personnel. The President has all the authority he needs under Article II (of the Constitution) to respond, and how he responds is yet to be determined, but he has that authority to respond," Sen. Lindsey Graham, a South Carolina Republican who is considered hawkish on foreign policy, said on Fox News Tuesday night. "It was an act of war by a regime that for the last 40 years has been a cancer in the Mideast."

And here are his full tweets from this morning: