A senior defense official on Thursday fiercely denied that Pentagon officials have told Congress that there are connections between al-Qaeda and Iran. Amid ongoing recent tensions between Tehran and the United States, some lawmakers have alleged that the Trump administration is seeking to link the Sunni terrorist group and the Shia government as part of a case for war.

“Myself and multiple senior defense officials have delivered multiple classified briefings to members of Congress and their staff to keep them apprised of these threats” from Iran, Mick Mulroy, deputy assistant defense secretary for the Middle East, said in a statement in response to questions from Defense One. “In these briefings, none of the officials mentioned al-Qa'ida or the 2001 Authorization to Use Military Force,” he said, using an alternate spelling of al-Qaeda and referring to the post-9/11 congressional authorization to wage war on the terror group.

Further, Mulroy said, “At no time did congressional staff ask about the link between al-Qa'ida and Iran.”

The Pentagon continues to rely on the 2001 AUMF to operate against jihadist groups around the globe, including ISIS. Some lawmakers have said that the Trump administration is seeking to use the AUMF to authorize potential military action againstIran without seeking congressional approval.

Those fears are largely sparked by public remarks explicitly linking the two by Secretary of State Mike Pompeo, known for his hawkish views on Iran. “There is no doubt there is a connection. Period. Full stop,” Pompeo said during a Senate hearing in April.

And in a public hearing earlier this month, the State Department’s special representative on Iran, Brian Hook, declined to rule out using the 2001 AUMF. “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, deferring to department lawyers.

There are some documented connections between Tehran and al-Qaeda—but legal analysts say those murky connections likely do not meet the legal threshold for using the 2001 AUMF to authorize military action against Iran. Security analysts and former officials describe al-Qaeda and the Iranian leaders as having at most opportunistic ties, rather than an operational alliance. Iran is a Shiite nation while al-Qaeda is a hardline Sunni group; the two are often on opposing sides of regional conflicts. Analysts say that Iran often keeps tabs on al-Qaeda and there have been al-Qaeda members inside Iran at various points, but they have often been under house arrest. In 2016, the Obama administration sanctioned three al Qaeda members that it said were in Iran.

“I do not believe, for what it’s worth, the 2001 AUMF authorizes force against the state of Iran,” Rep. Mac Thornberry, Texas, the top Republican on the House Armed Services Committee, said in a hearing this month.

Mulroy said that he and a Defense Intelligence Agency official did brief lawmakers on “the historical and ongoing ties between Iran and the Taliban,” and “not al-Qa'ida.” (The Taliban are covered by the 2001 AUMF because they harbored al-Qaeda before the 9/11 attacks.) “The DIA representative described the historical ties between Iran and the Taliban, and I explained that these ties are widely and publicly known and referenced in articles and books.”

Mulroy’s remarks expose a potential division between the State Department and the Defense Department. Lawmakers say that the Pentagon has made clear it doesn’t believe it has the authority to strike Iran under the old authorization. Pompeo, meanwhile, has provided no such assurances.

“Pompeo is never going to answer a question on authorization, so I’m not saying it came from Pompeo,” Sen. Chris Murphy, D-Conn., said after a briefing in May. “But…from DOD they seemed to make it clear they did not have authorization beyond self-defense. I think they said, ‘We can’t use the [2001] AUMF’.”

Pompeo “did not say, ‘I want to go to Iran and I'm going to use 2001’,” Rep. Elissa Slotkin, D-Mich., a former Pentagon official, said during a House Armed Services hearing this month. But, she warned, “He referenced a relationship between Iran and al Qaeda.”

Some legal and political analysts believe that the administration’s alleged effort to use the old authorization is a red herring—a kind of national hangover left over from President George W. Bush’s inaccurate talk of a connection between Saddam Hussein and al-Qaeda as a justification for his 2003 invasion of Iraq. Depending on the circumstances, Trump likely wouldn’t need Congress’s approval to launch an initial strike.

And his attorney general, William Barr, is known to hold exceptionally broad views of presidential warmaking authority.

Article I of the Constitution gives Congress the exclusive power to “declare war”—but Article II provides the president with the authority to direct U.S. forces as commander in chief, including the power to act in self-defense to “repel sudden attacks” against the United States. Tension with Iran have been rising since May, culminating last week when Tehran shot down a U.S. surveillance drone over what the United States says were international waters. Trump ordered then canceled retaliatory strikes on Thursday.

“Sure, there may later be claims about AUMF coverage, but the precipitating event, if it happens, is going to be something like another tanker attack or today’s drone shootdown, and so long as what they want to then do is limited in scale the response can then be justified on an Article II theory,” Bobby Chesney, a national security professor at the Texas University School of Law, said in an email.

“Frankly, that might not be too implausible at that point.”

The scope of the president’s inherent warmaking powers has been an evolving debate since the early days of the country. Presidents across administrations have taken an increasingly expansive view of their warmaking authority, drawing lines around military activity determined to be below the threshold of war. Instead, presidents have used their Article II powers to claim legal authority to direct various combat operations, like President Obama’s use of airstrikes in Libya.

But in theory, even the president’s authority to strike defensively is not unlimited. In order to continue any kind of long-term engagement, the White House would have to ask for permission after 60 days under the 1973 War Powers Act—although that law was arguably flouted under the Obama administration and has been fiercely disputed under the Trump administration.

The Trump administration insists that it is seeking negotiation, not war, with Iran.

But, Mulroy said, “the Department of Defense has taken prudent steps to adjust its force posture in the Middle East to strengthen its defenses, dissuade Iran from attacking U.S. forces, and ensure the president has a range of options available in the event of further attacks.”