After seeing the gruesome images of the chemical weapons attack in Syria, President Donald Trump authorized an attack on a Syrian air base, using dozens of cruise missiles.

"My attitude toward Syria and Assad has changed very much," the president said Wednesday ahead of the decision.

>> US fires more than 50 cruise missiles into Syria

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Sen. Rand Paul said Thursday that any military action taken against Syria by the U.S. would need congressional approval.

"Short of Congress voting on it, I'm opposed to illegal and unconstitutional wars," Paul said on Fox News Radio's "Kilmeade and Friends."

Paul sympathized with the victims of the human rights abuses being committed in Syria, but still urged calm deliberation instead of haste when it comes to potential military action.

“I have the greatest amount of sympathy. I can’t see those pictures. It’s heart-rending to see those pictures,” Paul said. “But (before) going to war, we have to decide, will it be better or worse? Will we improve our national security? Are we threatened currently by Syria, and if we go to war is (Syrian president Bashar al-Assad) likely to use less chemical weapons or more?”

“The bottom line is it’s horrific,” Paul added.

On Wednesday, Paul reminded the president via Twitter that he once opposed the Obama administration's intention to strike Syria in 2013, and also that Trump said at the time that any such action would require congressional authority.

Paul said he was one of the congressional leaders in 2013 who demanded President Obama consult Congress before the administration conducted any military strikes in Syria.

"I see the vote on whether to go to war in very personal terms. I will not vote to send my son, your son or anyone's daughter to war unless a compelling American interest is present," Paul said in a video response to Obama's 2013 address on Syria.

“I am not convinced that we have a compelling interest in the Syrian civil war,” Paul said at the time.

On Friday, Rand released a statement reiterating Congress’ role in decisions regarding military action.

“While we all condemn the atrocities in Syria, the US was not attacked,” he said. “The president needs congressional authorization for military action, and I call on him to come to Congress for a proper debate on our role.”

Other government officials agreed that Trump should consult congressmen.

Disclaimer: Jack Hunter co-authored the 2011 book “The Tea Party Goes to Washington” with Paul Rand.