Boris Johnson condemned Jeremy Corbyn for "consistently siding with terrorists" in an extraordinary attack during Thursday's SunTalks debate.
The Foreign Secretary was taking part in The Sun's event, alongside Emily Thornberry, Sir Vince Cable, and Patrick O'Flynn.
Johnson claimed: "Only months after the Brighton bombing, he invited convicted IRA killers into the Houses of Parliament."
The remark immediately drew consternation from Thornberry and several members of the audience, but Johnson wasn't finished.
He continued: "He is a man who has consistently sided with terrorists and people who oppose the values of this country.
"He's a man who, in my view, would do serious damage to the reputation of this country abroad, to international alliances, and to the UK economy.
"It think it would be catastrophic, and for me, there's only one answer to that: vote for Theresa May and the Conservatives."