WASHINGTON — Administration officials are briefing Congress on what they say are ties between Iran and Al Qaeda, prompting skeptical reactions and concern on Capitol Hill that the White House could invoke the war authorization passed in 2001 as legal cover for military action against Tehran.
As tensions between the United States and Iran have surged, Secretary of State Mike Pompeo and Pentagon officials have told members of Congress and aides in recent weeks about what they suggest is a pattern of ties between Iran and the terrorist group going back to after the Sept. 11, 2001, attacks, officials said.
They have stopped short of telling lawmakers or aides in large group settings that the 2001 authorization for the use of military force from Congress, which permits the United States to wage war on Al Qaeda and its allies or offshoots, would allow the Trump administration to go to war with Iran. President Trump has said he does not want a war, but he ordered 2,500 additional troops to the region in the last month in response to what American officials said was a heightened threat.
Statements tying Iran and Al Qaeda by Mr. Pompeo and other officials point to the potential for the administration to justify invoking the 2001 authorization, some lawmakers say. And when asked in recent weeks by lawmakers and journalists whether the administration would use the 2001 authorization, Mr. Pompeo has deflected the questions.
“They are looking to bootstrap an argument to allow the president to do what he likes without coming to Congress, and they feel the 2001 authorization will allow them to go to war with Iran,” said Senator Tim Kaine, Democrat of Virginia.
Mr. Kaine, a member of the Armed Services and Foreign Relations committees, declined to discuss details of classified briefings, but said senior administration officials had “talked about Iran providing safe haven to Al Qaeda.”
Mr. Pompeo, a West Point graduate and former C.I.A. director, visited United States Central Command in Florida on Tuesday to talk about Iran with military commanders as acting Defense Secretary Patrick M. Shanahan announced his resignation.
In a classified briefing that Mr. Pompeo gave on May 21 with Pentagon officials to the full House, “he discussed the relationship between Iran and Al Qaeda,” said Representative Elissa Slotkin, Democrat of Michigan.
She said Mr. Pompeo’s talk of that relationship in both public and private settings and his refusal to answer questions on a potential use of the 2001 authorization “raises the specter that to him, the relationship between Iran and Al Qaeda gives the administration that authority.”
Ms. Slotkin, a former C.I.A. analyst and Pentagon official who has worked in Iraq, added, “Any of us working on national security should be looking at any talk of ties between senior Iranian leaders and Al Qaeda with a real skeptical eye.”
On Monday, two Pentagon officials gave a classified briefing on Iran to legislative aides in which they mentioned Al Qaeda ties, according to a person with direct knowledge of the session.
That surprised the aides, who then pressed the officials — Michael P. Mulroy, the Pentagon’s deputy assistant secretary for the Middle East, and a Defense Intelligence Agency representative — on their assertions. Lawmakers are expected to ask Brian Hook, the State Department’s special representative on Iran, about war authorization when he appears at a House committee hearing on Wednesday.
Iran is a majority Shiite Muslim nation while Al Qaeda is a hard-line Sunni group whose members generally consider Shiites to be apostates. The two have often fought on opposing sides of regional conflicts, including the Syrian war.
Any relationship between Iran and Al Qaeda is one of convenience and not a real alliance, said current and former American officials, and there is no public evidence that Tehran has allowed Al Qaeda operatives to plot attacks on the United States from Iran or offered a haven for large numbers of fighters.
Lawmakers are wary of officials using links between Iran and Al Qaeda as a pretext for war because the administration of President George W. Bush talked of links between Saddam Hussein and Al Qaeda in 2002 to build a case for the invasion of Iraq. There were never close ties between the two.
The question of whether Mr. Trump might strike Iran has intensified since early May, when the White House announced military movements because of what American officials said was new intelligence showing a heightened threat against American interests from Iran or allied militias.
Mr. Trump then announced a deployment of 1,500 more troops to the Middle East, and on Monday he said he was sending 1,000 more. The administration has blamed Iran for two sets of oil tanker attacks. Iranian officials said Monday that their country would soon breach limits on uranium enrichment set by a 2015 nuclear deal from which Mr. Trump withdrew more than a year ago.
The possibility of war against Iran has invigorated efforts by Democratic and some Republican lawmakers to limit the president’s war powers. On Tuesday, two Republican senators, Rand Paul of Kentucky and Mike Lee of Utah, joined with Mr. Kaine and three other senators to send a letter to Mr. Trump saying “Congress has not authorized war with Iran and no current statutory authority allows the U.S. to conduct hostilities against the government of Iran.”
Mr. Paul pressed Mr. Pompeo in a Senate committee hearing in April to declare that the administration would not use the 2001 authorization to go to war with Iran. Mr. Pompeo said he preferred to “just leave that to lawyers,” then stressed ties between Al Qaeda and Iran: “There is no doubt there is a connection. Period. Full stop.”
On Sunday, Mr. Pompeo refused to answer when he was asked three times on CBS News’ “Face the Nation” whether the administration had the legal authority to attack Iran.
In his May 21 classified presentation to the House, Mr. Pompeo went into more detail on the Al Qaeda ties, said Ms. Slotkin and other lawmakers. Representative Matt Gaetz, a Florida Republican who is an ally of Mr. Trump, said in a committee hearing last week that administration officials made remarks in the classified May briefing that pointed to the idea that the 2001 authorization permitted “hostilities toward Iran.”
After the Sept. 11 attacks and before American forces bombed Afghanistan, more than a dozen senior Al Qaeda members fled to Iran. The circumstances under which they lived there were murky, but some senior officials, including Saif al-Adel, were apparently detained by Iran and later traded in a supposed prisoner swap with a Qaeda branch in Yemen.
Terrorism analysts say Hamza bin Laden, a son of Osama bin Laden, was in Iran at the time. He is now believed to be in Pakistan or Afghanistan and is considered a rising Qaeda leader. He dislikes Iran because he and his mother were imprisoned for years there, said Ali Soufan, a former F.B.I. terrorism investigator.
Mr. Al-Adel and other Qaeda officials have had freedom of movement in Iran at times, said Bruce Hoffman, a senior fellow for counterterrorism and homeland security at the Council on Foreign Relations.
Some military strikes against Iran would not require congressional permission, legal experts say. One potential such action would be a bombing of the Natanz nuclear facility, an option debated over the years by American and Israeli military officials.
Attorney General William P. Barr also has unusually broad views of a president’s power to unilaterally start even a major war.
The long-simmering discussion of presidential war powers in Congress has come to a boil in recent months, with bipartisan groups of lawmakers in both chambers introducing legislation that would place limits on the president.
The measures have found some support among moderate Republicans and constitutional conservatives who think the president’s ability to wage war should be limited.
“I do not believe, for what it’s worth, the 2001 A.U.M.F. authorizes force against the state of Iran,” Representative Mac Thornberry of Texas, the top Republican on the House Armed Services Committee, said during a hearing last week.