President Donald Trump uses a White House cell phone that isn’t equipped with sophisticated security features designed to shield his communications, according to two senior administration officials – a departure from the practice of his predecessors that potentially exposes him to hacking or surveillance.

The president, who relies on cellphones to reach his friends and millions of Twitter followers, has rebuffed staff efforts to strengthen security around his phone use, according to the administration officials.

The president uses at least two iPhones, according to one of the officials. The phones – one capable only of making calls, the other equipped only with the Twitter app and pre-loaded with a handful of news sites – are issued by White House Information Technology and the White House Communications Agency, an office staffed by military personnel that oversees White House telecommunications.