Dissident republicans were behind a deliberate attempt to kill police officers during rioting in north Belfast, the PSNI has said.
Rioters attacked police with petrol and blast bombs
Nine devices were thrown in total - six of them exploding.
Defending their operation, the police said 22 of the new type baton rounds were fired only after they came under bomb attack.
About 100 police officers were injured, but only two required hospital treatment.
The trouble began when nationalists attacked police after an Orange Order parade passed the Ardoyne shops area.
Police fired the new baton rounds known as attenuated energy projectiles (AEP), which were introduced last month.
Petrol bombs and three blast bombs, as well as bottles and bricks, were thrown at the police during disturbances on Tuesday.
Assistant Chief Constable Duncan McCausland said the trouble was clearly orchestrated but added that Sinn Fein President Gerry Adams and MLA Gerry Kelly did make efforts to calm the situation.
It is understood dissident republicans linked to the Continuity IRA were responsible for the most serious attacks. Several arrests were made.
The new style baton rounds are intended to present a reduced risk of causing serious or fatal injuries.
Baton rounds were last used in Northern Ireland in September 2002.
SDLP policing spokesman Alex Attwood said: "The SDLP has consistently and strongly opposed the use of any plastic bullets and the purchase of the AEP.
"Even though no plastic bullets had been fired for nearly three years, the SDLP repeats that their use last night or any other time is not acceptable to the party or to the nationalist community."
'A lethal threat'
One police officer was seriously injured and has been undergoing surgery in hospital. The extent of his injuries are not clear, but his condition is not believed to be life threatening.
The most serious violence against the police was in the Brompton Park area. A car was hi-jacked and burned and police used a water cannon on rioters.
Earlier on Tuesday, in agreement with police, 15 protesters were allowed to stand on a wall overlooking the route as the Orangemen passed holding aloft a banner saying 'make sectarianism history'.
Superintendent Gary White, who was in charge of the police operation, said the violence had clearly been premeditated.
Council workers have been clearing debris from roads after the riot
"We've used water cannon and various other tactics, and we retain the right to use whatever tactics are necessary when we're faced with a lethal threat," he added.
Speaking on Wednesday, Security Minister Shaun Woodward said the trouble which erupted at the Ardoyne shops area was "disappointing", but warned that it should be seen within a bigger picture.
"Let's be careful that 150 yards of north Belfast are not used to completely distort the picture of what was, by and large yesterday, a very successful parading day," he said.
"The reason for that is that people were involved in talks and dialogue."
Mr Woodward commended the work of the police.
He also paid tribute to nationalist and unionist politicians who got involved in dialogue. He said that everyone should be prepared to talk.
Sinn Fein North Belfast assembly member Gerry Kelly said lives could have been lost in the disturbances and that dialogue was "fundamental".
Speaking after Tuesday's rioting, the DUP's North Belfast MP Nigel Dodds said republicans either had no control of the situation or no desire to exert that control.
Ulster Unionist leader Sir Reg Empey said an overall solution needed to be found on the parades issue and called on the secretary of state to begin talks in the autumn.
Meanwhile in Londonderry, seven police officers were injured as 52 petrol bombs were thrown during rioting early on Wednesday.
Eleven people were arrested by police, who are trying to identify those involved in the trouble in both the Cityside and Waterside areas.
The Twelfth of July Orange Order parades mark the victory of the Protestant Prince William of Orange over the Catholic King James II at the Battle of the Boyne in 1690.