Boeing announced on 11 December the signing of a deal with Iran Air worth $16.6 billion at list prices for 50 737 Max 8s, 15 777-300ERs and 15 777-9s, with deliveries beginning in 2018.
The 80-aircraft order is “within the terms” of an export license approved by the US Treasury Department last September, Boeing says.
Boeing adds that the sale was “coordinated closely with the US government throughout the process leading up to the sale”.
Although the product of a controversial agreement to freeze Iran's alleged nuclear weapons programme, the sale comes at a critical moment for Boeing.
The contract would raise Boeing's net order total in 2016 to 548 aircraft, which is still about 230 sales short of the company's annual target with less than three weeks to go.
But the deal could still be complicated by political decisions.
Incoming US president Donald Trump, who takes office next month, opposes the nuclear agreement with Iran that permits the sale of commercial aircraft.
The Treasury department has complied with the terms of the nuclear agreement by clearing Airbus and Boeing to export commercial aircraft.
It's not clear if the Iran Air's orders will survive if the Trump administration seeks to withdraw from the nuclear agreement, which involves five other countries.
Trump already attacked Boeing on Twitter on 6 December, calling for the cancellation of an allegedly $4 billion Air Force One replacement programme due to "out of control" costs.
Boeing chief executive Dennis Muilenburg spoke to Trump by phone the next day. In a television interview after the meeting, Trump said he will “work it out with Boeing”, while noting that he will renegotiate the price of the deal.
Upon announcing the Iran Air order, Boeing emphasises the importance of preserving American jobs, a top priority for Trump's government. “Boeing's US supply chain currently supports more than 1.5 million US jobs,” the company says.