Determining why a Boeing Co. passenger jet flown by China Eastern Airlines Corp. plummeted to the ground from 29,000 feet (8,840 meters) is a thorny task in itself. Now, politics risks complicating the investigation and amplifying the fallout.

With relations between Washington and Beijing at their lowest ebb in years, the probe into China¡¯s worst aviation disaster in more than a decade ¡ª the crash of a U.S.-made plane run by a Chinese, state-owned airline ¡ª has turned the two archrivals into reluctant bedfellows.

Both sides stand to lose if the investigation becomes politicized, ensnared in a wider fight for dominance between the two superpowers that¡¯s touched everything from trade and the origins of the coronavirus to the war in Ukraine.