US military police only resorted to using tear gas against Black Lives Matter protesters in June when they couldn't get their hands on a 'heat ray', a whistleblower has alleged.
On June 1, amid huge protests across the US over the death of George Floyd at the hands of Minneapolis police, US President Donald Trump wanted a photo taken outside a historic church in Washington DC.
Before he could, protesters had to be moved.
National Guard Major Adam DeMarco, responding to questions posed by lawmakers, said he received an email from the Defense Department enquiring if they had a heat ray - formally known as an 'Active Denial System' (ADS) - or a sonic weapon called a 'Long-Range Acoustic Device' (LRAD) which they could use to clear the protesters.
The email said the heat ray "can immediately compel an individual to cease threatening behaviour".
DeMarco told them the National Guard had neither, so law enforcement instead used other tactics against the peaceful protesters, including pepper bullets and tear gas, according to numerous reports.
The Defense Department confirmed the inquiry, telling the Washington Post it was just a "routine inventory check", without elaborating.
The ADS, developed in the 1990s and 2000s, has never been used in combat. It was deployed in Afghanistan but never fired, commanders fearing the Taliban would seize on its propaganda potential and claim US troops were microwaving locals.
While it's meant to cause an "overwhelming" burning sensation and cause "intolerable" pain, in theory it's meant to be physically harmless. The waves it generates aren't meant to be able to penetrate skin, but at least one person who took part in testing suffered second-degree burns, the Post reports.
Use of the ADS was also considered as a way to stop migrants crossing the border with Mexico in 2018, but shut down by then-Secretary of Homeland Security Kirstjen Nielsen, the New York Times reports.
The LRAD is capable of emitting piercing loud noises, but can also be used to warn large crowds of what's about to happen. Police said they used an LRAD to do just that, but DeMarco said no one there even had one, and protesters said they had no warning before police started their attack.
The American Civil Liberties Union has called for a criminal investigation into the use of force against the protesters in June.
"Our government shouldn't be conspiring to use heat rays against us for exercising our constitutional rights," the group tweeted.