When President Trump calls old friends on one of his iPhones to gossip, gripe or solicit their latest take on how he is doing, American intelligence reports indicate that Chinese spies are often listening — and putting to use invaluable insights into how to best work the president and affect administration policy, current and former American officials said.

Mr. Trump’s aides have repeatedly warned him that his cellphone calls are not secure, and they have told him that Russian spies are routinely eavesdropping on the calls, as well. But aides say the voluble president, who has been pressured into using his secure White House landline more often these days, has still refused to give up his iPhones. White House officials say they can only hope he refrains from discussing classified information when he is on them. […]

American spy agencies, the officials said, had learned that China and Russia were eavesdropping on the president’s cellphone calls from human sources inside foreign governments and intercepting communications between foreign officials.

The officials said they have also determined that China is seeking to use what it is learning from the calls — how Mr. Trump thinks, what arguments tend to sway him and to whom he is inclined to listen — to keep a trade war with the United States from escalating further. In what amounts to a marriage of lobbying and espionage, the Chinese have pieced together a list of the people with whom Mr. Trump regularly speaks in hopes of using them to influence the president, the officials said.