Four people, including a mother and her son, have been arrested in the West Midlands on suspicion of Syria-related terrorism offences.
Police said one of the men arrested, aged 45, from Hall Green, is suspected of attending a terrorist training camp and facilitating terrorism overseas.
A 36-year-old man from Shirely and a woman, 44, along with her 20-year-old son, were arrested on suspicion of facilitating terrorism overseas.
All four are being held at a police station in the West Midlands for questioning.
Police said the suspects' homes are being searched by officers from the West Midlands Counter Terrorism Unit. Vehicles and electronic equipment are being removed for forensic analysis as part of the operation.
Police stressed this was a pre-planned operation and there was no immediate risk to the public.
Head of investigations for West Midlands Counter Terrorism Unit, Det. Supt. Shaun Edwards said: "All four arrests are connected. They were pre-planned and intelligence-led. There was no immediate risk to public safety.
"We continue to urge anyone planning to travel to Syria to read the advice issued by the Foreign Office."