Later in the article: "Foreign governments are well aware of the risk, and so leaders like Mr. Xi and Mr. Putin avoid using cellphones when possible." Also see China Mocks Report It Tapped Trump’s iPhone (and Plugs Its Own Competitor) | NYT
"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.When Trump Phones Friends, the Chinese and the Russians Listen and Learn | NYT
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."