Army bomb disposal experts monitor an abandoned and burnt out van on the Crumlin Road in Belfast
First Minister Peter Robinson said those behind a series of security alerts in Belfast on Monday were "beneath contempt".
The M1 motorway between Moira and Lurgan has reopened after it was closed due to an abandoned vehicle.
Alerts near police stations at Tennant Street, North Queen Street, Kingsway and Blacks Road were all hoaxes.
"Those who would try to destabilise and destroy Northern Ireland will fail. We won't be going back," said Mr Robinson.
The Hillview Road in the Oldpark area of north Belfast has reopened.
Meanwhile, army technical officers examined a vehicle at Oldpark Road, which, it was believed, was hijacked and abandoned. The road has not been closed.
The Upper Springfield Road in Belfast is passable after a fire in a hijacked lorry was put out.
Alerts on the Andersonstown Road and at the Stormont Hotel on the Upper Newtownards Road in Belfast were also declared hoaxes.
A van which was burnt out close to Holy Cross church on the Crumlin Road in the city also caused disruption, the police said.
There were reports that two cars had been hijacked in the Kilwilkie area of Lurgan.
A number of vehicles have been hijacked and set alight across Belfast
Peter Robinson said those responsible would not succeed in "dragging Northern Ireland backwards".
"The criminal terrorists responsible for the series of bomb scares and hijackings have no support whatsoever in the community," he said.
Sinn Féin MLA for North Belfast, Carál Ní Chuilín, said they had "no strategy".
"These actions are wrong and counterproductive to anything that our communities want," she added.
"I would like the spokespeople of those behind these alerts to come forward and explain how this will in any way achieve a united Ireland."
Ulster Unionist leader Sir Reg Empey said the disruption was caused by "republican elements who are determined to pursue their warped campaign regardless of the cost".
"As this is yet another test for our community, I appeal again for people to remain calm and not under any circumstances to retaliate."
East Belfast Alliance MLA Naomi Long said the hoax alerts were "despicable".
"These micro groups can not and will not be allowed to de-rail the progress made in recent years," she said.
"I would urge anybody with any information about any of these security alerts to contact the police."
SDLP deputy leader Alasdair McDonnell MP said those responsible were "enemies of peace and progress".
"The hijackings and alerts are intent in wrecking the new agreed Ireland, we have worked so hard to achieve," he added.