Intel evacuated thousands of employees from its Belfast plant on Tuesday morning after police received a "credible" threat from a caller claiming to be from the Islamic State.
The US computer chip giant moved to remove workers from the campus after a caller purporting to be from the terrorist network phoned police at 5.30am warning of 12 devices that had been placed across the complex in Leixlip, Co Kildare.
Intel employs approximately 4,000 people at the facility and those who were evacuated were not allowed to access their vehicles until after the area had been searched and given the all-clear.
The site's employees have since returned to work.
The threat came hours after Pro-Islamic State (Isis) hackers took control of the official Twitter account of US Central Command.
Its timeline was littered with a series of messages praising the Islamist group and threatening US soldiers before it was suspended.