The Trump administration is coming under increased pressure from Congress to kill a landmark deal between Boeing and an Iranian airline known for engaging in terrorism over concerns the Western airline company would enable Tehran's transfer of militant fighters across the region, according to multiple sources, who told the Washington Free Beacon the administration is likely to nix the multi-billion dollar deal.

The Obama administration's nuclear agreement with Iran paved the way for U.S. aerospace corporation Boeing to ink a deal with Iran's state-controlled airline, Iran Air, which was recently caught using its commercial planes to ferry Iranian militants to regional hotspots.

The Trump administration's recent decision to increase economic pressure on Iran and rework the nuclear agreement has prompted a shift in thinking on the Boeing sales, which require special licenses from the Treasury Department to move forward, according to U.S. officials and those in Congress who are familiar with the shift in thinking on the issue.

The Trump administration is said to be viewing the sales with an increasingly critical eye and is moving, at this point, toward killing the sales, according to these sources, who pointed to concerns over Iran Air's use of commercial airplanes for terrorism purposes.

While the sale could create new American jobs, U.S. officials and others told the Free Beacon the administration and Congress will not permit any business deal that enables Iran's military efforts and pursuit of regional dominance.

The Free Beacon first disclosed in August that Congress has been investigating new evidence that Iran Air has been ferrying militants to Syria and other regional hotspots in violation of international laws. It is likely that the Obama administration withheld information about this behavior in order to help promote the nuclear agreement.

There is mounting concern in the Trump administration and Congress that Iran would use a fleet of new Boeing planes to boost its regional intervention in hotspots such as Syria, where Iranian-backed militants have repeatedly attacked American coalition forces.

While a final decision has not yet been made on whether to kill the deal, top officials have been critical of the Boeing agreement and do not view it as in the United States' national security interests.

"This is a careful consensus, ongoing process," according to one source familiar with administration deliberations on the issue. "They're adding up everything in all the columns. They're not just deciding ‘well it's more important for Boeing to make money' or ‘well it's more important to prevent Iran from sending troops to Assad.'"

"But I wouldn't count on the Trump to administration to easily allow any company, let alone an American company, to fuel Iran's war machine. Their priority is the opposite," the source said.

Congressional leaders who have opposed the nuclear agreement, as well as Boeing's efforts to sell Iran a new fleet, told the Free Beacon that the administration's new stance on Iran cannot be effective if it fails to kill the airline sales.

"Iran Air is the terror-supporting transport-arm of Iran's Islamic Revolutionary Guard Corps (IRGC). It would be foolish to allow Iran Air to buy hundreds of jets from Western companies the carrier can use to continue shipping jihadis and arms to the Assad regime and terror proxies," Rep. Peter Roskam (R., Ill.), a vocal opponent of the deal, told the Free Beacon. "To have a truly effective and coherent Iran policy, we need to clamp down on every single entity that supports the IRGC, including Iran Air. There should be no exceptions."

Roskam petitioned the Trump administration last week to formally kill the deal based on Iran Air's continued relationship with the IRGC, which the Trump administration recently designated as a terror organization.

"Preventing the sale of aircraft to Iran while its commercial aviation sector serves as a client of the IRGC is fully aligned with the administration's goals of raising the cost of Iran's destabilizing behavior and countering the IRGC," Roskam wrote. "By targeting a core Iranian weapons transport method, the U.S. can proactively weaken Iran's future ability to send weapons and militiamen from Iran to Syria to fight for Bashar al-Assad and Hezbollah."

One senior congressional official familiar with the Boeing issue told the Free Beacon the Trump administration should move forward with efforts to kill the deal, which lawmakers in the House have voted to do multiple times.

"The administration is right to reconsider the failing nuclear agreement with Iran," the source said. "Any deal that is unable to verifiably and permanently prevent Iran from acquiring nuclear weapons should be terminated."

"The agreement we have today simply puts Iran on a patient glide path toward nuclearization," added the source, who could only speak on background about deliberations surrounding the Boeing deal. "The House has already voted multiple times to block the sale of commercial airliners to the regime in Tehran. We will continue to work to prevent U.S.-made airplanes from being repurposed as weapons of war."

Rep. Sean Duffy (R., Wis.) told the Free Beacon that any Trump administration bid to nix the deal would be backed by congressional opponents of Iran's terror activities.

"The Trump administration has done a tremendous job of reasserting American leadership in the world by standing up to thuggish regimes after eight years of retreat," Duffy said. "President Trump should continue to put America First and prevent Boeing sales from going to the world’s leading state-sponsor of terror, Iran."

The Treasury Department, which handles licensing issues surrounding Boeing's deal, would not comment on where the issue stands, telling the Free Beacon, "Treasury's Office of Foreign Assets Control does not comment on specific licensing requests or determinations."

However, Sigal Mandelker, Treasury's under secretary for terrorism and financial intelligence, stated in a recent speech that Iran's use of commercial planes for terrorism purposes would not be tolerated by the Trump administration.

Iran's regional terror operations are "supported by entities like U.S.-designated Mahan Air, which carries weapons, fighters, and money to the Assad regime and its supporters like Hezbollah in Syria," according to Mandelker, who said that new sanctions on the IRGC and other entities tied are coming down the pike.

"Over the last 10 months, since this administration took office, OFAC, one of the offices that I oversee, has issued seven tranches of sanctions, designating 72 targets in China, Iran, Lebanon, and Ukraine in connection with the IRGC, Iran's ballistic missile program, support for terrorism, and human rights abuses," Mandelker said. "And we are continuing to ramp up the economic pressure on Iran's illicit networks using all of the tools and authorities at our disposal."