SEOUL (Reuters)

A second Boeing (NYSE:BA) jet intended for use by a Chinese airline was heading back to the U.S. on Monday, flight tracking data showed. This seems to be another victim of the tit-for-tat bilateral tariffs launched by President Donald Trump in his global trade offensive.

The 737 MAX took off from Boeing’s Zhoushan completion center near Shanghai on Monday morning and was on its way to the U.S. territory of Guam, according to data from flight tracking website AirNav Radar. Guam serves as one of the stops for flights on the approximately 5,000-mile (8,000-km) route between Boeing’s U.S. production hub in Seattle and the Zhoushan completion center, where planes are delivered to Chinese carriers.

On Sunday, a 737 MAX with the livery of China’s Xiamen Airlines completed the return journey from Zhoushan, landing at Seattle’s Boeing Field.

It remains unclear which party decided for the two aircraft to return to the U.S. This month, Trump raised baseline tariffs on Chinese imports to 145%, to which China retaliated with a 125% tariff on U.S. goods. Should a Chinese airline attempt to take delivery of a Boeing jet, it would face crippling tariffs, especially given that a new 737 MAX has an estimated market value of around $55 million, as reported by aviation consultancy IBA (EBR:IBAB).

The jet had previously flown from Seattle to Zhoushan just under a month ago. Boeing has not immediately commented on this situation.

The return of the 737 MAX jets, which are Boeing’s best-selling model, highlights ongoing disruptions in new aircraft deliveries resulting from the breakdown of the aerospace industry’s long-standing duty-free status. This tariff war, along with changes in delivery agreements, comes during Boeing’s recovery from nearly five years of import freezes on 737 MAX jets and earlier trade tensions.

Experts suggest that confusion over evolving tariffs could place numerous aircraft deliveries in limbo. Some airline CEOs have indicated they might defer new aircraft deliveries rather than incur hefty duties.