President Donald Trump’s alleged unsecured internet and telephone use “could endanger sensitive U.S. national security interests,” a group of Democratic U.S. senators argued on June 7, criticizing the commander in chief for what they called “reckless” conduct.

In a letter to the National Counterintelligence and Security Center, four senators requested a threat assessment to determine if sensitive government information has been exposed due to Trump’s reported habit. The senators added that if Trump has been using the vulnerable devices to communicate, “it represents a grave danger to U.S. national security.”

“We are especially concerned about recent reporting that President Trump has eschewed the advice of counterintelligence experts and opted to use unsecured commercial devices,” Senators Martin Heinrich D-NM., Richard Durbin D-Ill., Ron Wyden D-Ore., and Dianne Feinstein D-Calif., said in the letter.

On May 21, the news website POLITICO reported that Trump uses a cellphone without “sophisticated security features designed to shield his communications,” citing two senior administration officials.

The Department of Homeland Security has found signs of digital surveillance equipment near the White House and at other sensitives sites in Washington, D.C., the agency wrote in a May 22 letter.

Use of cellphones and other electronic equipment is tightly regulated for employees in many areas of the U.S. government.

“Government officials with access to classified information must abide by strict security protocols that limit when, how, and in what manner they communicate with others,” the senators wrote.

Trump’s alleged unsecured cellphone use would be a departure from the previous administration.

For years, former President Barack Obama said he used a modified Blackberry device. For security reasons, Obama said the phone did not have a recorder in it.

In 2016, Obama told late-night host Jimmy Fallon that he finally received a new smartphone. But for security reasons, government officials told Obama that “it doesn’t take pictures, you can’t text … you can’t play your music on it.”

Obama compared the new device to a play phone that a three-year-old would use as a toy.

“That’s basically the phone I’ve got.”