PARIS (Reuters) - France will react with the greatest firmness after a school teacher was beheaded on the street of a Paris suburb on Friday after he had shown his pupils cartoons of the Prophet Mohammad, Prime Minister Jean Castex said on Saturday. “Through one of its defenders, it is the Republic which has been struck in the heart by Islamist terrorism,” Castex wrote on Twitter. “In solidarity with its teachers, the State will react with the greatest firmness so that the Republic and its citizens live, free! We will never give up. Never.”