President Donald Trump declared the Islamic Republic of Iran made a “big mistake” after the commander of their Revolutionary Guard Corps shot down a U.S. drone as Republican lawmakers take different stances on a possible military conflict between the two nations.

In response to the news, Trump published a tweet Thursday morning announcing that the Islamic Republic made a “very big mistake” in shooting down a U.S. drone over the Strait of Hormuz.

Check it out:

Iran made a very big mistake!

— Donald J. Trump (@realDonaldTrump) June 20, 2019

The military strike by Iran brought up questions of legality regarding the Trump administration’s authority to retaliate under the 2001 authorization to use military force (AUMF).

The State Department’s special envoy for Iran Brian Hook would not answer directly questions about whether or not the Trump administration believed it could use AUMF against Iran during a House Foreign Affairs Committee hearing on Wednesday, asserting that the administration would “comply with the law” if “military force” was needed to protect “national security interest.”

“If the use of military force is necessary to defend U.S. national security interest, we will do everything that we are required to do with respect to congressional war powers and we will comply with the law,” Hook said.

His testimony came after Secretary of State Mike Pompeo told the Senate Foreign Relations Committee there was “no doubt” that there was a “connection” between “Iran and al Qaeda.”

Republican lawmakers are split on whether or not the president has the authority to retaliate to the attack without congressional approval.

Florida Senator Marco Rubio (R-Fla.) — who sits on the Senate Committee on Foreign Relations — told reporters that he believes Trump does have the authority as the action would be “defensive” in nature.

“They don’t have to, because they’re not talking about offensive activities, they’re talking about defensive activities,” said the Florida Republican.

Senator Lindsey Graham (R-S.C.), who also serves on the Senate Foreign Relations Committee, told reporters that he was “good to go” regarding the issue of legal authorization.

Senator Rand Paul (R-Ky.) said that he believed that retaliation by the Trump administration using the 2001 authorization would be “inappropriate,” adding that he believed there are “no credible links” between the Islamic Republic and al Qaeda.

“I think every president tries to make the case that Congress can’t tell them what to do on foreign policy or war. They’re wrong. […] I will oppose any president, Republican or Democrat, who thinks they can go to war without congressional approval,” the Kentucky senator told reporters.

A bipartisan group of senators — including Paul, Senator Tim Kaine (D-Va.), and Senator Mike Lee (R-Utah) — wrote a letter to the president expressing that they were “concerned” about a potential military conflict between the two nations.

“Given that growing risk, we want to reiterate that, as of this date, Congress has not authorized war with Iran and no current statutory authority allows the U.S. to conduct hostilities against the Government of Iran,” they wrote in the letter.

On Thursday, it was reported that Iran shot down a U.S. drone over the Strait of Hormuz, claiming that the drone was violating Iranian national airspace and saying that the action was to send “a clear message” to America.

The U.S. pushed back on the claim, asserting that the drone was in international airspace.