Britain's Defence Secretary Gavin Williamson | Daniel Leal-Olivas/AFP via Getty Images UK defense secretary: Brits fighting for ISIS should be destroyed Britain should do everything possible to ‘destroy and eliminate’ threat posed by returning Islamic State fighters.

Britons who have joined ISIS should never be allowed to return to the U.K., British Defense Secretary Gavin Williamson said in an interview published Thursday.

"Quite simply, my view is a dead terrorist can’t cause any harm to Britain," Williamson told the Daily Mail. "I do not believe that any terrorist, whether they come from this country or any other, should ever be allowed back into this country."

Williamson added that the U.K. "should do everything we can do to destroy and eliminate" the threat posed by returning ISIS fighters.

According to the Daily Mail, more than 800 Brits are believed to have traveled to fight for ISIS in Iraq and Syria. Half have returned to the U.K. and around 130 are believed to be dead.