Constitutional law expert Alan Dershowitz told Newsmax on Thursday that the War Powers Act would unduly hinder President Donald Trump's ability to threaten Iran into a favorable outcome, acknowledging the issue is a "subtle one."

Dershowitz joined "The Record With Greta Van Susteren" to discuss a bipartisan group of lawmakers who are looking to limit Trump's ability to order U.S. strikes on Iran's nuclear capabilities.

The War Powers Resolution of 1973 was passed to limit a president's power to commit U.S. armed forces into a conflict without the approval of Congress.

Dershowitz said he agrees with that if a president wanted to invade and occupy a country. But that's not what's happening in Iran, and Trump needs the ability to do what he does best, Dershowitz said — threaten Iran and reach a deal or, barring that, destroy their nuclear capabilities.

"The issue in this case is a subtle one. The president has to be able to threaten. What do you think President Trump's strategy is by postponing for two weeks his decision whether to bomb Fordow? It's to put pressure on the other side," Dershowitz said. "And if the president alone couldn't put the pressure and couldn't say to Iran, 'If you don't do this within two weeks, we're going to come in and bomb Fordow,' if he had to say, 'Look, if you don't do this in two weeks, I'm going to go to Congress' — and I know there are people in Congress who are opposed to this, Republicans and Democrats — it would eliminate the ability of the president to effectuate foreign policy and military policy by threats."

Trump is reportedly mulling whether to use a bunker-busting bomb on Iran's Fordow fuel enrichment plant near Qom, the nuclear site nestled roughly 300 feet below ground level. Israel does not have bombs that could neutralize the subterranean nuclear site.

"That would particularly affect President Trump, who is the threatening president, the deal-making president. And I think this two-week thing is a perfect example of why it's necessary to give the president the kind of authority he has," Dershowitz added.

However, when it comes to the Vietnam War and Korean War, Dershowitz said neither of those should have happened with Congressional approval.

"A war can consist of simply aiding an ally like the United States is helping Israel defend itself against missiles ... and it could be a full-fledged ground invasion with an occupation. And the real issue arises when the latter occurs. And it did occur," Dershowitz said. "The latter occurred, obviously, during the Korean War, during the Vietnam War, there were full-fledged invasions with boots on the ground, and even then it was regarded as a political question to challenge whether or not this was permissible under the Constitution."

"But a fair reading of the Constitution does suggest strongly that before any kind of a full-fledged war is permissible with treasure and blood of Americans, that there ought to be congressional approval," he added.

GET TODAY NEWSMAX+:

NEWSMAX is the fastest-growing cable news channel in America with more than 30 million people watching!

Reuters Institute reports NEWSMAX is one of the top news brands in the U.S.

You need to watch NEWSMAX today.

Get it with great shows from Rob Schmitt, Greta Van Susteren, Greg Kelly, Carl Higbie, Rob Finnerty – and many more!

Find the NEWSMAX channel on your cable system – Go Here Now

BEST OFFER:

Sign up for NEWSMAX+ and get NEWSMAX, our streaming channel NEWSMAX2 and our military channel World at War.

Find hundreds of shows, movies and specials.

Even get Jon Voight's special series and President Trump's comedy programs and much more!

Watch NEWSMAX+ on your smartphone or home TV app.

Watch NEWSMAX anytime, anywhere!

Start your FREE trial now: NewsmaxPlus.com