Federal police inquired about whether the National Guard had a “heat ray” officers could use against protesters congregated near the White House in early June, NPR reports. The Provost Marshal of Joint Force Headquarters National Capital Region emailed the Washington, D.C. National Guard to request a sound cannon known as an LRAD and a microwave weapon called an Active Denial System, or ADS. The ADS “provides a sensation of intense heat on the surface of the skin,” according to the email, and disperses crowds via an “overwhelming effect.” Federal authorities have been reluctant to use it since its development 20 years ago over questions of efficacy and ethics. Major Adam DeMarco, a member of the National Guard, has filed for whistleblower protection in reporting the exchange. DeMarco responded to the request, “The D.C. National Guard was not in possession of either an LRAD or an ADS.” At the protest in question, federal authorities used tear gas to disperse demonstrators before President Donald Trump posed for a photo while holding a bible in front of the church on Lafayette Square.