Iran is providing high-level al Qaeda operatives with a clandestine sanctuary to funnel fighters, money and weapons across the Middle East, according to Trump administration officials who warn that the long-elusive, complex relationship between two avowed enemies of America has evolved into an unacceptable global security threat.

With the once-prominent Islamic State receding from the spotlight, The Washington Times has learned that the administration is focusing increasingly on the unlikely alliance between Iran and al Qaeda, with what some sources say is an eye toward establishing a potential legal justification for military strikes against Iran or its proxies.

Skeptics have long doubted that Iran, which this year marked its 40th anniversary as a Shiite Muslim theocracy, could find common cause with a radical Sunni Islamist group such as al Qaeda, but U.S. officials argue that a confluence of interests — and a common enemy in the U.S. and its allies — has brought a level of covert cooperation and coordination that has reached new heights.

The Authorization for Use of Military Force (AUMF) passed by Congress in the days after the 9/11 attacks provided the legal framework for President George W. Bush to order U.S. military action against the Taliban for harboring Osama bin Laden and al Qaeda fighters in Afghanistan. The law has underpinned the U.S. counterterrorism campaign and has largely gone unchanged for the past 17 years through three presidential administrations.

Congressional and legal sources say the law may now provide a legal rationale for striking Iranian territory or proxies should President Trump decide that Tehran poses a looming threat to the U.S. or Israel and that economic sanctions are not strong enough to neutralize the threat.

Top U.S. officials argued in recent interviews that the partnership between a resurgent al Qaeda and Shiite Iran has been one of the most underreported and misunderstood aspects of global Islamic extremism over the past two decades.

The dynamic is nuanced, the history is fraught, and the two sides remain distrustful and occasionally in conflict — as evidenced by the deadly suicide bomb attack last week blamed on an al Qaeda-linked group in Iran’s southeastern region. U.S. officials, however, insist that a mountain of hard evidence shows the two have made a calculated decision to work together.

It’s an alliance, they add, that the U.S. and its allies in the region cannot tolerate. It’s also an argument that dovetails nicely with deep skepticism Mr. Trump and his top aides have expressed for the regime in Tehran, which they accuse of fomenting instability and threatening key U.S. allies across the Middle East.

“Since 9/11, the Iranian regime has given sanctuary to senior AQ members, and it remains unwilling to bring these terrorists to justice,” said Nathan A. Sales, State Department coordinator for counterterrorism, who has been a key player on the administration’s Iran policy team since Mr. Trump appointed him to the post in 2017.

“This partnership of convenience between Tehran and AQ is both dangerous and unacceptable, and it further reinforces Iran’s status as the world’s leading state sponsor of terrorism,” Mr. Sales told The Times in an exclusive interview.

The recently unclassified version of the U.S. intelligence community’s annual Worldwide Threat Assessment for 2019 did not delve deeply into Iran-al Qaeda ties, but it contained a map that highlighted Iran for its presence of an al Qaeda “Affiliate, Element or Network.”

The latest State Department report on global terrorism trends issued in the fall went further. It laid out the case for at least a working relationship between Iran and al Qaeda: “Iran remained unwilling to bring to justice senior al Qaeda members residing in Iran and has refused to publicly identify the members in its custody. Iran has allowed al Qaeda facilitators to operate a core facilitation pipeline through Iran since at least 2009, enabling al Qaeda to move funds and fighters to South Asia and Syria.”

Washington has long listed Iran as the world’s top state sponsor of terrorism. It cites the estimated $1 billion a year that Tehran sends to a host of recognized terrorist organizations, most notably the Lebanon-based Shiite group Hezbollah and the Palestinian Sunni group Hamas. The listing, however, falls far short of the heft carried by a congressionally backed AUMF because it allows the White House to order only sanctions, not military strikes, against Iran.

The administration has not publicly commented on whether it is considering strikes on the grounds where Iran is willingly offering safe haven to al Qaeda leaders. But some lawmakers and other sources say the discussion is taking place among Mr. Trump’s top aides, including National Security Adviser John R. Bolton and other sharp critics of Iran, who stress that all options are on the table for dealing with Tehran’s institutionalized support for terrorism and its nuclear weapons potential.

Since Mr. Trump last year pulled the U.S. out of a 2015 multilateral deal negotiated by the Obama administration to limit Tehran’s nuclear program, the administration has been using harsh unilateral sanctions to starve its economy and to limit the amount of money it sends to terrorist groups. While other signatories to the 2015 deal, which curbed Iran’s nuclear programs in exchange for a lifting of international sanctions, say they want to preserve the agreement, U.S. officials say the pressure campaign is bearing fruit.

“Iran is still the world’s leading state sponsor of terrorism. They organize, train and equip militias around the region with the ambition of creating a Shia corridor,” said Brian Hook, the administration’s special representative for Iran and a pivotal figure inside the State Department on Iran policy. “Our focus has been to go after the money that allows Iran to do this, and we have a lot of economic leverage being outside the Iran nuclear deal. We are also working with nations to restore deterrence against Iran’s missile testing and proliferation.

“We are very pleased with the progress that we are making, with the results of our campaign of economic pressure,” he said in an interview. “There’s a lot more to come.”

Direct connections

Sources say the willingness of Iran and al Qaeda to join forces grew after the U.S. aerial bombardment of Afghanistan’s Tora Bora cave complex in December 2001 — an assault that left many powerful terrorist leaders searching for a new home.

Although the Iranian regime initially condemned the 9/11 attacks, Mr. Bush quickly included Tehran in what he called an “axis of evil” along with Iraq and North Korea. Government assessments show that Tehran adopted a complex stand toward al Qaeda early in the U.S. war on terrorism, placing conditions on the group’s presence in its country and insisting that al Qaeda not conduct operations on Iranian soil or recruit Iranian citizens.

Last week’s attack in southeastern Iran would seem to violate those conditions, though many details behind the planning of the assault are not clear. Jaish al Adl, a group with close ties to al Qaeda, claimed responsibility for the blast, which killed 27 members of the Islamic Revolutionary Guard Corps.

Although the al Qaeda-linked group said it was behind the attack, Iranian President Hassan Rouhani instead blamed the U.S. and Israel.

“The crime will remain as a ‘dirty stain’ in the black record of the main supporters of terrorism in the White House, Tel Aviv and their regional agents,” Mr. Rouhani said. The attack took place in the poor, restive Sistan-Baluchistan province, which is home to many of Iran’s Sunni Muslim minority.

Despite the attack, officials say some of al Qaeda’s most influential figures have been granted sanctuary in Iran.

In response, the U.S. has placed “bounties” on some of those men, including a $10 million reward for information leading to the capture of Yasin al-Suri, whom U.S. intelligence has described as the head of the terrorist group’s Iran operation.

State Department documents describe al-Suri as a pivotal figure in the Iran-al Qaeda relationship and in the broader terrorist nexus across the Middle East. Documents say al-Suri helped oversee the transfer of al Qaeda fighters and weapons through Iran to Pakistan, Afghanistan and elsewhere.

U.S. intelligence has been closely watching al Qaeda operations in Iran for years, although information from the classified case files has rarely been made public. One of the more prominent albeit mysterious cases involved Muhsin al-Fadhli, a key figure in the Iran-al Qaeda partnership who was killed by U.S. bombs in Syria five years ago.

The 2014 strikes were aimed at the so-called Khorasan Group, a shadowy al Qaeda-linked organization. The group’s leader, al-Fadhli, was a top target in those attacks and in the years prior had taken over “leadership of the Iran-based AQ facilitation network,” government documents show.

In 2016, the Obama administration imposed economic sanctions on several senior al Qaeda figures in Iran: Faisal Jassim Mohammed al-Amri al-Khalidi, Yisra Muhammad Ibrahim Bayumi, and Abu Bakr Muhammad Muhammad Ghumayn. Treasury Department officials said the men helped acquire and transfer arms, raised money and pursued other illicit activities on behalf of al Qaeda.

The Iran-al Qaeda nexus stretches beyond simply offering a hideout for prominent al Qaeda figures. Foreign policy analysts who have studied the origins and evolution of the connection point to terrorist strikes that were planned with the tacit support of Tehran, especially if those attacks targeted Iran’s Sunni Muslim rivals.

In 2003, for example, al Qaeda attacked residential compounds in Riyadh, Saudi Arabia, killing 35 people. Those strikes were planned and directed by al Qaeda figures Saif al-Adel and Sa’ad bin Laden, both of whom were given sanctuary in Iran and used their home base there to plot the assault.

In 2008, al Qaeda operative Ahmad Wali Siddiqui stood trial in Germany for plotting terrorist attacks in Europe. In court, Siddiqui said he and other al Qaeda fighters used Iran as a launchpad to travel throughout the Middle East and Europe with minimal attention.

Regional analysts say the course of events since 2001, including the U.S.-led invasion of Iraq in 2003, the death of bin Laden in 2011, the Arab Spring political revolts, the Syrian civil war, the rise and receding of the Islamic State as a rival to al Qaeda have all played roles in the complicated relationship between al Qaeda and Iran.

Nelly Lahoud, a former terrorism analyst at the U.S. Military Academy and now a New America Foundation fellow, was one of the first to review documents seized from bin Laden’s hideout in Abbottabad, Pakistan. She wrote in an analysis for the Atlantic Council this fall that the bin Laden files revealed a deep strain of skepticism and hostility toward the Iranian regime, mixed with a recognition by al Qaeda leaders of the need to avoid a complete break with Tehran.

In none of the documents, which date from 2004 to just days before bin Laden’s death, “did I find references pointing to collaboration between al Qaeda and Iran to carry out terrorism,” she concluded, although the interplay between the two was clearly complex and conflicted.

One captured 2007 document, apparently written by an al Qaeda operative, concluded that, in the wake of the 2003 U.S. invasion of neighboring Iraq, “Iranian authorities decided to keep our brothers as a bargaining chip.”

Although many pieces of the Iran-al Qaeda relationship have been exposed through news reporting and government documents, analysts say few in Washington have stood up to paint a full picture of the alliance and just how dangerous it remains.

“The Trump administration is right to focus on Tehran’s full range of malign activities, and that should include a focus on Tehran’s long-standing support for al Qaeda,” said Bradley Bowman, senior director of the Center on Military and Political Power at the Foundation for Defense of Democracies, a leading Washington foreign policy think tank.

The foundation circulated an analysis in recent days asserting that the “Iran-al Qaeda relationship should command the attention” of the Financial Action Task Force (FATF), a global body devoted to setting standards to combat illicit finance. “Iran’s support for al Qaeda is incompatible with FATF standards,” the analysis said.

It remains to be seen what action the FATF, which is meeting this week in Paris and is currently headed by Marshall Billingslea, U.S. assistant Treasury secretary for terrorist financing, may take against Iran.

Justification for war?

Last week, Mr. Trump made clear that the White House is keenly focused on Iran’s connection with terrorists and suggested that more action is on the horizon.

“My administration has acted decisively to confront the world’s leading state sponsor of terror: the radical regime in Iran,” he said during his State of the Union address. “To ensure this corrupt dictatorship never acquires nuclear weapons, I withdrew the United States from the disastrous Iran nuclear deal. And last fall, we put in place the toughest sanctions ever imposed on a country.

“We will not avert our eyes from a regime that chants ‘death to America’ and threatens genocide against the Jewish people,” said Mr. Trump, referencing Tehran’s violent anti-American and anti-Israel rhetoric.

Behind the scenes in Washington, there is increasing speculation that the White House could make a case for military strikes using the existing AUMF, which authorizes the president to use all “appropriate force” to target those who “planned, authorized, committed or aided” the 9/11 attacks on America, which killed nearly 3,000 people.

Legal analysts say the administration likely would have a strong argument.

“For many reasons, I think we need an updated AUMF, but if the facts show Iran or any other nation is harboring al Qaeda, that’s a circumstance which would make the argument for the applicability of the 2001 AUMF quite strong,” said retired Air Force Maj. Gen. Charles J. Dunlap Jr., now executive director of the Center on Law, Ethics and National Security at Duke University.

“After all, al Qaeda was directly responsible for the 9/11 attacks Congress was addressing at that time,” he said. “Since Congress chose not to put a ‘sunset’ provision in the resolution, it remains good law.”

For political and strategic reasons, Congress has repeatedly been unable to pass a new force authorization law to more narrowly define the president’s right to strike terrorist groups.

Ironically, an attempt last summer to craft a new AUMF failed partially because some Democrats feared the text could be twisted to greenlight military action against Iran.

Last week, some lawmakers on Capitol Hill downplayed the notion that attacks on Iran could be justified by an al Qaeda connection, and they argued that the current AUMF simply wouldn’t apply.

“There are certainly al Qaeda officials and leadership in Iran, in and out of Iran, but the relationship with the government is somewhat unclear,” said Sen. Angus S. King Jr., Maine independent and a member of the Senate Select Committee on Intelligence.

“We have the right to react if Iranian forces attack our people in some other part of the Middle East,” he said. “But if we’re talking about some kind of pre-emptive action in Iran, I don’t think that would be authorized under the AUMF.”

⦁ Lauren Meier contributed to this report.