Loyalist paramilitaries have warned they will step up their terror campaign.
The Red Hand Defenders made the threat following a pipe bomb at offices used by Martin McGuinness.
The group has also admitted planting a booby trap device under a former republican prisoner's van in Armagh.
Mr McGuinness was on holiday when the RUC cleared around 40 buildings in the Burn Road area of Cookstown, Co Tyrone.
Police confirm that a crude pipe bomb was discovered and dealt with by Army explosives experts.
They also disclosed that a mercury tilt switch had been fitted to the device found under the vehicle at Ashley Avenue, Armagh. It is the first time such a device has been used in Ulster for some time.
The Red Hand Defenders sparked a wave of revulsion when it admitted murdering Protestant teenager Gavin Brett in Glengormley, Co Antrim last month.
And after claiming to have planted the latest two devices it vowed: "Our campaign will increase."
Earlier, a little known group calling itself the Loyalist Action Force said it was responsible for the Cookstown device.
A third alert took place in Derry where the Foyle Bridge was sealed off because of a bomb warning.