(Reuters) -Boeing is set to restart deliveries of its 787 Dreamliner to China within days, a source told Reuters, a step that could pave the way for China to also end a more than four-year freeze on deliveries of Boeing (NYSE:BA)’s profit-making 737 MAX.

Juneyao Airlines, a privately-owned Chinese carrier, will receive in Shanghai a new 787 Dreamliner from Seattle, the source familiar with the matter said. It could take off as soon as Thursday, the person said.

In a sign the U.S. planemaker is moving closer to resuming 737 MAX deliveries, trade publication The Air Current said on Wednesday Boeing had this month won a key clearance from China’s aviation regulator, the Civil Aviation Administration of China (CAAC).

Chinese orders and deliveries of Boeing planes have been largely suspended since 2019 after two fatal 737 MAX crashes in 2018 and 2019 led to the MAX being grounded worldwide in 2019.

The safety bans have been lifted, as existing MAX planes – Boeing’s most profitable model – are flying inside China, but new deliveries have remained on hold.

“We continue to support our customers in China and will be ready to deliver for our customers when that time comes,” Boeing said in separate responses to the Juneyao news and the Air Current reports.

The CAAC’s deputy head on Dec. 8 told a Boeing executive in Beijing the planemaker was welcome to deepen its development in the Chinese market, Reuters reported. The Air Current, citing unidentified sources, said the regulator’s clearance was granted that day.

Individual MAX deliveries to China still need approval from China’s National Development and Reform Commission (NDRC), the Air Current report said.

The CAAC and NDRC did not immediately respond to Reuters’ requests for comment.

A 737 MAX designated for China Southern Airlines flew from Boeing Field in Seattle to Boeing’s nearby facility in Moses Lake, Washington, and back on Wednesday afternoon, according to data from flight tracking website FlightRadar24.

Analysts from Jefferies and Deutsche Bank said in investor notes that it appeared to be a customer acceptance flight – a test flight operated by an airline pilot that occurs before delivery.

For Boeing, restarting deliveries would symbolize the re-opening of doors to one of the world’s most important aerospace markets, which Boeing projects will compose 20% of the world’s aircraft demand through 2042.