The Obama administration likely hid information about Iran illicitly ferrying militants into Syria on commercial aircraft in order to promote the landmark nuclear deal and foster multi-billion dollar business deals with Tehran's state-controlled airline sector, according to lawmakers and other sources familiar with the matter.

The Washington Free Beacon first disclosed last week that congressional leaders are calling for an investigation into Iran for using its state-controlled air carrier, Iran Air, to ferry militant fighters into Syria, where they are taking up arms in defense of embattled President Bashar al-Assad.

Photographs provided to Congress show Iran using Iran Air to ferry these soldiers between 2016 and 2017, in part when the Obama administration removed sanctions on Iran Air and promoted multi-billion dollars sales between the carrier and aircraft manufacturer Boeing, which is seeking to provide Iran Air with a fleet of new planes that many suspect will be used to carry terrorist fighters and weapons into regional hotspots.

This behavior violates international laws governing the nuclear deal and has now led lawmakers and others to accuse the Obama administration of downplaying Iran's illicit activity in order to promote the nuclear deal and ensure Tehran receives a new commercial fleet.

Multiple senior Obama administration officials, including former secretary of state John Kerry, traveled the globe to promote trade with Iranian companies, including Iran Air, at the same time Iran was found to be ferrying militants into Syria. Lawmakers and others suspect the Obama administration either hid or downplayed this information in order to preserve the nuclear deal.

"The Obama administration lifted sanctions against Iran Air as a political concession during nuclear negotiations with Iran, not because of any change in its activity," Rep. Peter Roskam (R., Ill.), one of the lawmakers calling for an investigation into Iran's use of commercial aircraft for military purposes, told the Free Beacon.

"Using social media and public flight tracking websites, any person with a computer can document Iranian military transports to Syria on commercial jets," Roskam said. "The Obama administration undoubtedly knew Iranian airliners were being used to fuel Assad's atrocities in Syria, but the administration officials who were globetrotting as Tehran's chamber of commerce trying to shore up the nuclear deal didn't care."

"Iran Air continues to support the Iran-Assad war machine to this day, and the Trump administration must hold the airline accountable and work to stop them," the lawmaker said.

Roskam and a delegation of other Republican congressmen petitioned the Trump Treasury Department last week to investigate photographic evidence showing Iran using Iran Air to ferry militants into Syria.

"Iran's use of commercial aircraft for military purposes violates international agreements as well as Iranian commitments under the JCPOA," or Joint Comprehensive Plan of Action, the lawmakers wrote, according to a letter first obtained by the Free Beacon. "We believe these photos mandate a thorough investigation of these practices and a comprehensive review of Iran's illicit use of commercial aircraft."

The lawmakers demand the Trump administration freeze all licenses that would permit the deal between Boeing and Iran Air to move forward.

Rep. Ron DeSantis (R., Fla.), a vocal opponent of the Iran deal who sits on the House Foreign Affairs Committee, told the Free Beacon that the Obama administration ignored evidence of Iran's illicit military activity in a bid to appease Tehran and forward the nuclear agreement.

"As the Obama administration was shipping palettes of cash to Iran, the mullahs were sending militants to wage jihad in Syria," DeSantis said. "The Obama administration turned a blind eye to this and other transgressions because it was so intent on delivering major sanctions relief to the world's leading state-sponsor of terrorism, the Iranian government."

The Treasury Department did not respond to multiple Free Beacon requests for comment on the matter.

The Treasury Department has vowed in the past to consider and investigate any new evidence revealing Iran's illicit use of commercial aircraft, but it remains unclear if U.S. officials are actually following through on this promise.

Administration insiders have expressed confusion over the matter, saying they are unsure where Trump officials stand on scrapping the nuclear agreement.

Multiple proponents of ending the deal were recently removed from the White House's National Security Council and it appears that those officials supporting the deal currently are now the majority voice. This includes Secretary of State Rex Tillerson and National Security Adviser H.R. McMaster.

Administration insiders say the Obama administration's aggressive efforts to promote trade with Iran and lay the groundwork for massive deals such as that formed with Boeing placed the current administration in a complicated position.

Boeing says the deal would create scores of U.S. jobs, but those opposing the deal say American workers should not be aiding Iran's illicit activity.

"The Obama administration actively politicized and downplayed intelligence about Iran to preserve the deal," said one veteran congressional adviser working on the issue. "They had State remove references to Iranian terrorism, had Justice ignore Iranian sanctions-busters and proliferated, and even had Energy buy off Iranian deal violations. So of course they had Treasury look the other way while the Iranians were facilitating Assad's mass slaughter."

Michael Rubin, a former Pentagon adviser and expert on rogue regimes, said champions of the Iran deal had knowledge of Iran's illicit behavior, but downplayed this information to push the nuclear agreement forward.

"The Boeing deal is where corruption meets national security. One of the biggest proponents of the Iran deal was Thomas Pickering, a former ambassador whom the Obama administration brought in to assuage Congress and re-up its talking points in the media," Rubin said. "Pickering never acknowledged, however—even to Congress—that at the time he had a lucrative consulting gig with Boeing in order to enable that company to profit off any Iran deal."

Iran is seeking to purchase from Boeing a fleet much larger than its domestic needs require, another sign that points to the regime's desire to use these commercial aircraft for military purposes, Rubin said.

"What the heck did the Obama team think Iran would do with its Boeings? If they tallied up Iran's annual air travel with the capacity offered by Boeing, they'd find that Iran was purchasing planes representing triple what Iran needed for its civilian transport," Rubin said. "Frankly, the Boeing deal should have resulted in as many red flags as if Iran said it wanted to purchase high explosives and rocket engines. But, national security and reality were far down Obama and Secretary of State John Kerry's lists of priorities."