A 31-year-old man has been arrested in connection with threats to kidnap and kill a serving police officer.
West Midlands Police said officers from its counter-terrorism unit arrested the man on Tuesday afternoon.
The arrest was made at property in the West Midlands, the force said.
The force had issued an alert to officers and staff after receiving an “anonymous but credible” tip-off and said it was taking the threat “extremely seriously”.
Officers have been urged to take extra precautions, including not wearing uniform during journeys to and from work.
Staff were first told on Monday night after the force received the call.
Officers were held on duty to be given the security reminder while others were told as they started their shifts.
Assistant Chief Constable Garry Forsyth said the information received related “to the safety of West Midlands Police officers and police staff”.
“We have taken the opportunity to remind all employees of the need to be vigilant. Our priority remains serving our communities and protecting them from harm,” he said.
“Officers remain on patrol and our staff continue to respond to calls for service as usual.”
The force remains on a “severe” level of terror alert.
“The status hasn't changed,” a representative said.
In October, the threat level to police officers across Britain was raised to substantial.
The national security level remains at severe, signifying a terrorist attack is highly likely.