A man is being questioned on suspicion of Syria-related terror offences after police raided a house in Sheffeld.
Detectives from the West Midlands Counter Terrorism Unit are today quizzing the 21-year-old suspect following his arrest on Friday.
He was one of four men arrested as part of the police operation, with a 26-year-old from Kent and a 19-year-old from Coventry also in custody today.
A 32-year-old from Margate has been released on bail pending further enquiries.
A West Midlands Police spokesman said: "Detectives from the West Midlands Counter Terrorism Unit are today questioning three men on suspicion of Syria-related terrorism offences.
"A 21-year-old man was arrested last Friday from an address in Sheffield and a 26-year-old man was arrested in Kent in the early hours of last Thursday.
"Warrants of further detention were granted on Friday for the 21-year-old and the 26-year-old and detectives have up to seven days before charging, releasing, bailing or applying to a court for a further extension of detention.
"A 19-year-old man was arrested from Coventry last night. Detectives have an initial 48 hours to question him.
"All three men continue to be questioned in the West Midlands.
"A fourth man, aged 32, was arrested from Margate on Friday. He was released on police bail on Saturday pending further enquiries.
"The arrests were pre-planned and intelligence-led. There was no immediate threat to public safety."