Boeing is grabbing headlines for its first-of-its-kind, $25 billion deal with Iran Air, Tehran’s state-owned airline.

But the American aerospace giant isn’t exactly publicizing the fact that it paid a lobbying firm to “monitor” the nuclear agreement that made its $25 billion sale to Tehran possible. Or that Boeing has on its payroll a former top Clinton administration official who used his clout to garner support in the corridors of powers for the Iran deal.

Thomas Pickering, one of the country’s most respected diplomats and a and former ambassador to Israel and the United Nations, has been quietly taking money from Boeing while vocally supporting the Iran nuclear deal—testifying before Congress, writing letters to high-level officials, and penning op-eds for outlets like The Washington Post.

Pickering confirmed via email—from his Boeing corporate email address—that he was on staff at the company from 2001 to 2006 and has been a paid consultant for them ever since.

“I was a Boeing employee from 1/2001 to 6/2006,” he emailed. “I was a direct consultant to Boeing from 7/2006 until 12/2015 when‎ contract for consulting was moved to Hills for my work.”

“Hills” refers to Hills & Company International Consultants, where Pickering is a principal. In a previous email, Pickering referred to his “contract arrangement with Boeing” in the present tense.

He didn’t respond to a follow-up email asking if he disclosed his relationship with Boeing when discussing Iran with members of Congress and with the press. The Daily Beast found no evidence that he made a habit of making such a disclosure, and will update this piece if we do.

News of the impending sale highlights just how much Boeing and Iran’s state-owned airline both stand to benefit from the nuclear agreement for which Pickering advocated. The fact that Pickering did not regularly disclose his relationship with Boeing—which, as is now obvious, had a massive financial interest in the implementation of the Iran nuclear agreement—has drawn criticism from government transparency advocates, who consider it to be a violation of ethical standards.

Neil Gordon—an investigator for the Project on Government Oversight, a Washington watchdog organization—said Pickering should have been upfront about his work for Boeing when testifying before Congress on the deal and making the case for it in op-eds for major publications.

“In Pickering’s case, he has a direct connection to Boeing, which I think should be disclosed,” he said.

“I think it’s necessary for the public debate,” Gordon added. “It’s necessary for the public to fully realize the participants’ financial interests. Some of them might have a direct financial stake in a particular outcome.”

Boeing, he added, clearly had a financial interest in the Iran nuclear agreement. The deal reopened the door to American business dealings with Tehran, which time and again had looked to restock its aging fleet of planes with newer, Western models.

Gordon compared it to a controversy in 2013 , when many think tank scholars and military experts arguing for a U.S. military presence in Syria didn’t disclose that they had financial ties to defense companies that stood to benefit from the intervention. Media outlets presented these commentators as independent, Gordon noted, when they weren’t. And, he added, Pickering’s situation is similar.

Over the past few years, Pickering has been one of the most vocal and visible advocates for the nuclear agreement with Iran. On June 19, 2014, he testified before the House Armed Services Committee about his views on the need for a comprehensive agreement with Iran. He did not mention Boeing in the disclosure form he provided to the committee prior to his testimony. Boeing also isn’t mentioned in his bio that the House kept on file .

Besides testifying before Congress, Pickering also signed a letter on July 7, 2015 , to congressional leadership, along with other former diplomats, urging them to support the nuclear agreement. That letter didn’t disclose his connection to Boeing, and it drew broad media coverage, including from the Huffington Post , Politico , and the AP . None of those reports noted his work for Boeing. The White House also cited the letter in its publication “The Iran Nuclear Deal: What You Need to Know About the JCPOA.” Boeing is not mentioned anywhere in that document.

Rep. Mark Takai cited “hours discussing the matter with Amb. Thomas Pickering” in a press release announcing his support for the Iran deal, and Sen. Dick Durbin name-checked him in a Senate speech arguing for the deal.

Additionally, Pickering co-authored a Washington Post op-ed arguing that the deal “could help save Iraq”—and, of course, without disclosing his ties to Boeing. And he wrote an op-ed for Tablet on July 27, 2015, called “A Guide for the Perplexed: The Iran Nuclear Agreement” arguing for the deal. Again, no mention of Boeing. Tablet described him as a former diplomat—and not as a current consultant to a company that stood to make billions off the agreement.

His bio at the National Iranian American Council, which generally backs a cooling of tensions between Washington and Tehran and where he serves as an advisory board member, notes that he worked at Boeing until 2006 but does not note that he still consults for the company. Same for his bio at the anti-nuclear weapon group Global Zero. His bio at The Iran Project doesn’t mention Boeing at all.

Pickering wasn’t the only person on Boeing’s payroll who closely followed the Iran nuclear agreement. A lobbying report filed with the government on Oct. 19, 2015, shows the company paid Monument Policy Group LLC between $5,000 and $50,000 between July 1 and Sept. 30, 2015, to do lobbying work on the agreement, as well as other issues. A separate report—accessible, like the first one, through a public database—shows Boeing spent between $5,000 and $4,956,000 lobbying from Oct. 10, 2015, through the end of that year. It lists “U.S.-Iran Relations” as an issue it worked on. The Washington Free Beacon noted these reports in a story published Jan. 29 of this year.

Tim Neale, a spokesman for Boeing, said the company did not take a position on or lobby for the Iran nuclear deal and the negotiations that preceded it.

“Monument Policy Group passively monitored congressional debate on the nuclear agreement for Boeing, but did not engage congressional offices on the agreement,” he added. “Our own lobbying activity in Q4 was in response to questions we were getting about the potential for airplane sales to Iran, plus misconceptions about the potential for Ex-Im Bank financing of such sales, which we felt were important to correct.”

Boeing’s decision to sell planes to Iran Air has already generated some controversy in Congress. Rep. Peter Roskam, an Illinois Republican, wrote an editorial for USA Today promising to do everything he can to stop the deal from going through.

“Boeing says it must go wherever Airbus goes,” he wrote, citing the fact that the company’s European competitor recently signed a deal to sell planes to Iran Air. “But history is a merciless disciplinarian to those who make themselves complicit in evil because ‘someone else was doing it.’”

State Department spokesman John Kirby said on Tuesday that it “welcomes” Boeing’s plan to sell planes to Iran. And backers of the Iran deal say the sales are an integral part of realizing the promise of sanctions relief.

Trita Parsi—the president of the National Iranian American Council—said Boeing’s deep interest in the agreement didn’t surprise him. Nor did the company’s desire to keep a low profile on this issue.

“Obviously Boeing wants this deal with Iran, but it’s a tricky one,” he said. “It has a lot of political dimensions. That is something Boeing would probably prefer not to deal with.”

“Once the deal was approved, I’m not surprised that Boeing would step things up a little bit,” he said of the company’s additional lobbying in the months after the U.S. signed on to the Iran nuclear agreement.

Parsi also said Boeing could have drawn unwelcome criticism from the public and from Congress if it publicized its support for the nuclear agreement.

“I think more than anything else, they were trying to make sure they would put up some sort of buffer against too many members of Congress jumping on the train of condemning Boeing for doing something that it is now legal for them to do,” he said.

Parsi added that Boeing’s tentative agreement to sell planes to Iran Air will be critical to the success of the Iran nuclear agreement. If Boeing and Iran Air can finalize and successfully implement the multibillion-dollar sale, it will be easier for other American companies to do business with Iran, he said. On the other hand, if criticism from political leaders and the public makes completing the deal too politically costly for Boeing, then other companies will be unlikely to follow its lead. And if that happens, then Iran’s sanctions relief will be in word only—the country won’t benefit from the U.S. decision to lift some sanctions, and that could disincentivize its leaders from holding up their end of the agreement.

“If the Iranians end up de facto not getting sanctions relief, the deal will collapse,” he said. “That’s right now the biggest threat to the sustainability of the deal.”