Two Democratic Senators have questioned the security of Donald Trump’s smartphone, three weeks after it was reported that the president was using an unsecured, off-the-shelf Samsung Android device. Senators Claire McCaskill and Tom Carper — both of whom serve on the Homeland Security Committee — put a list of questions about Trump’s phone habits in a letter to Secretary of Defense Jim Mattis dated February 9th and released today.

McCaskill and Carper say that the recent reports suggesting that the president may still be using his old device were “troubling” — in part because it doesn’t leave a record of what he’s been saying. “While it is important for the President to have the ability to communicate electronically,” the letter reads, “it is equally important that he does so in a manner that is secure and that ensures the preservation of presidential records.”

I look forward to hearing from @DeptofDefense about the protective measures being taken for President Trump’s use of a personal smartphone pic.twitter.com/47cZeSn1bw — Senator Tom Carper (@SenatorCarper) February 13, 2017

But more of a problem may be Trump’s smartphone security. “Hackers often target smartphones in an attempt to obtain sensitive, personal information from the user,” the letter reads. “Security risks associated with the use of an unsecured phone include hackers' ability to access the device to turn on audio recording and camera features, as well as engaging surveillance tools that allow location and other information tracking features,” the Senators say. “These vulnerabilities are among the reasons why national security agencies discourage the use of personal devices.”

The Verge showed last week how hackers could access the messages, microphones, and even cameras of unsecured smartphones, allowing third parties to covertly record information stored on the phone or discussed in its vicinity. Any hackers who used similar methods to break into smartphones in the president’s office could already have seen sensitive information this week, when Trump’s aides used their smartphone to illuminate sensitive documents relating to North Korea’s recent missile launch.

McCaskill and Carper have given Mattis a deadline of March 9th to issue a reply to their concerns. It’s not clear, however, whether the Senators will be able to finally make Trump give up his apparently beloved Android — especially if, like Obama’s Secret Service-issued BlackBerry, a secure device wouldn’t let the president on Twitter.