Four hundred extra police from across Britain are being sent to Northern Ireland.
It follows a night of rioting in Belfast that left 32 officers injured and left DUP MP Nigel Dodds in need of hospital treatment.
More than 600 officers were already in the region supporting the PSNI operation as Orange Order protests over the contested parade routes spiralled into violence in North Belfast.
The violence has been widely condemned with Sinn Féin saying Unionist leaders need to take responsibility for the violence.
The clashes started when loyalist marchers were stopped from passing into a nationalist area - at one point - men wielding swords charged police lines.
The Tanaiste Eamon Gilmore has also spoken outagainst last night's clashes saying the violence and disrespect for the rule of law is an affront to the decent people of the city and of this island.
Sinn Féin Assembly member Gerry Kelly says the Orange Order are responsible for the riots:
