The US Congress will examine the long-awaited sale of fighter jets to Qatar, Kuwait and Bahrain, the last step before a formal notification.

Sources familiar with the deal tell FlightGlobal the informal notification has begun. Qatar has requested 36 Boeing F-15E Strike Eagles, with an option for a total of 72, sources say. Kuwait has requested 28 Boeing F/A-18 E/F Super Hornets, with an option for a total of 40 aircraft, although Kuwait has also considered a split buy that would include Eurofighter Typhoons.

Bahrain has expressed interest in the Lockheed Martin F-16.

"We are encouraged by continued progress and are hopeful to see further movement on Qatar and Kuwait fighter sales,” a Boeing spokeswoman says. “These sales are an important part of the future of the F/A-18 and F-15 fighter lines."

The Qatar and Kuwait sales come as a welcome boost to Boeing, which has slowed production of Super Hornets and EA-18G Growlers at its St. Louis, Missouri facility to two per month. In addition to continued orders from the US Navy, which requested 16 F/A-18s through fiscal year 2018, the possible Kuwait sale would extend the F/A-18 line through mid 2018. With the Navy and potential Kuwait orders, Boeing plans to continue building two Super Hornets per month into the 2020s, Dan Gillian, vice-president of F/A-18 and EA-18G programmes, told reporters in September.

"[It's] quite a different situation from two years ago," Gillian says. "We would have ended production in 2016, now we’re confident about building airplanes into the 20s."

In June, U.S. Navy Secretary Ray Mabus encouraged the foreign sales of Super Hornets to keep the production lines in St. Louis humming and costs down for the service. The Qatar sale would bring F-15 deliveries beyond its slated end in early 2019.

After languishing for two years, the three foreign sales are gaining traction after the US inked a $38 billion, 10-year military assistance package to Israel that included Lockheed Martin F-35s and the transfer of 10 Boeing F-15Ds that were excess defense articles from the US Air Force. That deal has helped quell Israeli concerns over the US delivering fighter jets to Gulf states it believes pose an existential threat.