President Trump has been handing out his cell phone number to world leaders, urging them to call him directly on it, the Associated Press reported Tuesday, a breach of protocol that raises security concerns about the president's communications.
Among the world leaders who have been given the president's cell phone number are Canadian Prime Minister Justin Trudeau and Mexican President Enrique Peña Nieto, according to the wire service. Trudeau is the only one who has spoken with Trump by cell phone so far, the report said.
Trump reportedly exchanged numbers with France's newly-elected President Emmanuel Macron as well. Macron spoke with Trump after his election victory, but French officials did not comment to the AP about whether the French leader planned to communicate with Trump on his cell phone.
The report comes just days after Trump wrapped up the first foreign trip of his presidency, which included stops at the Vatican, Israel, Saudi Arabia and attendance at the G-7 conference in Sicily with world leaders.
Trump's use of a cell phone for official communications raises concerns about the security of such calls, which are usually set up by White House staff on secure phone lines. Even if Trump is using a government-issued cell phone, the conversations could be open to surveillance, security experts said.
"If you are speaking on an open line, then it's an open line, meaning those who have the ability to monitor those conversations are doing so," Derek Chollet, a former Pentagon advisor and National Security official told the AP.
The White House did not respond to BuzzFeed News requests for comment.
Trump would likely not be the first high-level government official, or president, to use a cell phone to communicate with his counterparts, officials said. But if the president is making a habit of using a cell phone to communicate with foreign leaders it not only raises the possibility that the conversations can be intercepted, but also circumvents internal monitoring and review of presidential calls that normally takes place.
That monitoring and review, Chollet told BuzzFeed News, is essential to make sure promises are carried out, conversations are logged for future reference, and so staff is fully aware what the president is discussing with other heads of state.
Most phone calls between presidents are usually set up by the White House situation room, where staff tests the line to make sure it is secure. Calls are also monitored by staff and other US agencies, who take notes and prepare for any possible follow up required after a conversation.
But preparation for those phone calls is also extensive before they are made, Chollet told BuzzFeed News, including the developing of talking points, possible questions that could be raised, and a briefing with the president to make sure he is prepared.
Extensive preparation is not just essential for technological security of the call, he said, but for effective diplomatic navigation.
The extensive preparations help officials stay the course on any long-term policy, but help to make sure the president is not caught unaware during conversations with leaders.
"So if the person on the other line asks a question, the president has an answer and they don't come up with a response at the top of their head, or they don't promise something without knowing if its possible or not," Chollet said. "I think with an individual like Trump, there could be the danger that something could be misinterpreted and, secondly, there could be a promise made that can't be made for whatever reason."
Government officials have used cell phones in the past, he said, but the practice is not common and also requires officials to immediately and often brief their staff to make sure they are in the loop of what was discussed. Other US agencies are informed about the interactions.
"If you're the national security adviser, you want to know who the president is talking to," Chollet said. "You wouldn't want to find out second-hand from a foreign leader."
There is also the danger of cell phone conversations being picked up by outside government or agencies, he said. That is not usually a problem so long as both parties understand not to discuss classified material on the line.
"That takes discipline and understanding," he said. "If you're speaking on an open line, you just have to understand that everything you say will be heard by a bunch of people that you don't want to hear it."
Even if Trump's cell phone is not used by world leaders, experts said it could open the president to eavesdropping attempts by other nations.
"If you are Macron or the leader of any country and you get the cellphone number of the president of the United States, it's reasonable to assume that they'd hand it right over to their intel service," said Ashley Deeks, a law professor at the University of Virginia who previously worked as an assistant legal advisor for political-military affairs in the US State Department.
If the president's cell phone were to be breached by hackers, experts told BuzzFeed News, it wouldn't just be his conversations that could be compromised.
A hacked phone could be remotely controlled to use its camera and microphone, making it essentially a listening device in the president's pocket, John Michelsen, chief product officer of Zimperium, a security company that protects mobile devices from attack, told BuzzFeed News
Government issued cellphones would presumably have more protections, he said, but would still be vulnerable.
"It just makes me cringe because, in fact, his cell phone is the most single valuable asset to hack," Michelsen said. "What a hacker could do with a mobile phone is troubling to me."