The American intelligence community has no evidence that al Qaeda has cooperated with the Iranian government in its recent aggressive moves in the Persian Gulf region, a senior U.S. government official told members of Congress on Tuesday.

That finding, which was relayed to The Daily Beast by three sources familiar with the matter, could undercut a potential legal case for going to war with Iran if tensions between Washington and Tehran keep escalating.

The assessment was delivered in a classified briefing with dozens of House members on Capitol Hill. According to the three sources, one of the officials who briefed the members said the U.S. government does not have evidence of operational coordination between the Iranian government and the terrorist group responsible for 9/11 with respect to the current threat stream.

The significance of the admission is likely to divide lawmakers. Democrats who worry about the prospect of war between the U.S. and Iran will likely say that the lack of intelligence means the Trump administration cannot use Congress’s 2001 Authorization for Use of Military Force (AUMF) to fight al Qaeda as a legal basis to start a war with the regional power. Republicans, in contrast, are likely to view it as a non sequitur, arguing that the administration isn’t trying to start a war but rather to act in defense of U.S. interests and forces in the Gulf region.

Over the last decade, presidents from both parties have circumvented Congress when it comes to waging military campaigns. Presidents George W. Bush, Barack Obama, and Donald Trump have all used the 2001 AUMF to justify a wide range of military activity—drawing pointed but largely toothless criticism from Capitol Hill. Obama, for instance, used the 2001 AUMF to justify the American fight against the Islamic State, which did not exist in 2001.

Last month, Secretary of State Mike Pompeo publicly connected Iran and al Qaeda, calling the ties “very real.”

“They have hosted al Qaeda, they have permitted al Qaeda to transit their country,” said Pompeo, “There is no doubt there is a connection between the Islamic Republic of Iran and al Qaeda. Period, full stop.”

When Pompeo testified to the Senate Foreign Relations Committee last October, Sen. Rand Paul (R-KY) pressed him on whether the 2001 AUMF would permit a war on Iran.

“I would prefer just to leave that to the lawyers,” he said, as France24 reported.

Pompeo is not the only government official to see a connection between Iran and al Qaeda. In 2011, the Obama administration’s Treasury Department accused the two of forming an alliance to move arms and fighters.

In February of this year, The Washington Times, a conservative paper, ran a story citing anonymous Trump administration officials saying that Iran is “providing high-level al Qaeda operatives with a clandestine sanctuary to funnel fighters, money and weapons across the Middle East”—a claim the newspaper noted could be used to justify war.

Increased tensions between the U.S. and Iran have generated concern on the Hill about an escalatory spiral. Earlier this month, the U.S. moved an aircraft carrier strike group to the Persian Gulf, with administration officials saying Iranian proxies were threatening U.S. forces in the region. That came after the administration eliminated sanctions waivers for countries looking to buy Iranian oil and after the administration designated the Iranian Revolutionary Guard Corps as a terrorist group.

The Daily Beast reported last week that officials in multiple U.S. government agencies have assessed that Iran’s increasingly hostile behavior came in response to those moves.

A year ago, the Trump administration withdrew the United States from an international deal with the Iranian government intended to keep it from developing nuclear weapons by trading caps and insight on their program for targeted sanctions relief.