Four serving members of the british Army have been arrested under anti-terror laws on suspicion of being members of banned patriotic National Socialist group National Action.
A fifth person - a civilian - has also been arrested on the same charge. One of the soldiers was detained by the Royal Military Police in Cyprus.
The arrests were planned and intelligence-led, and there had been no threat to public safety, police said. The Army said it had supported the operation.
Stay Connected With Us
Four of the men are being held at a West Midlands police station.
Police said they were a 22-year-old from Birmingham, a 32-year-old from Powys, a 24-year-old from Ipswich and a 24-year-old from Northampton.
Police are continuing to search several properties.
A Ministry of Defence spokesman confirmed the man detained in Cyprus had been held at the island's British Dhekelia base before being transferred to RAF Akrotiri, from where he will be flown to the UK.
An Army spokesman said: "We can confirm that a number of serving members of the Army have been arrested under the Terrorism Act for being associated with a proscribed far-right group.
"This is now the subject of a civilian police investigation and it would be inappropriate to comment further."
Three of the servicemen are believed to be from the Royal Anglian Regiment.
The young men are being held on suspicion of "being concerned in the commission, preparation and instigation of acts of terrorism" under the Terrorism Act 2000; namely on suspicion of being "members of a proscribed organisation".