Washington DC - President Donald Trump raced to China's defense on Sunday as they faced accusations of supplying Tehran with satellite imagery that led to a strike which ended up killing three US soldiers.

"You know, when they say that China spies on us, I say you're right, and we spy on them too," Trump told reporters aboard Air Force One a day after a Wall Street Journal report accused Beijing of sharing crucial military intelligence with Tehran.

"They do what we do. They basically do what we do," Trump said when asked whether he'd raise the report with Chinese President Xi Jinping. "I think [Xi's] behaved reasonably well, and we've behaved reasonably well."

He quickly moved on to talk about the late Dolly Parton, whose music he had reportedly been playing aboard the presidential jet.

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The WSJ report alleged that Chinese entities supplied the Iranians with satellite images of the Muwaffaq Salti Air Base in Jordan, which Tehran then struck with missiles on July 17. Three US soldiers were killed in the attack.

Unnamed American officials cited in the Journal's reporting did not name the Chinese entities involved, and did not suggest that the government in Beijing was directly to blame.

Chinese officials asked for proof of the transfer of satellite imagery when prodded by US officials, and refused to acknowledge that Chinese companies were involved in providing Tehran with satellite images, the Journal reported.

The incident could deepen tensions between Washington and Beijing ahead of a planned state visit by Xi to the White House on September 24.