Five suspected ISIS members have been arrested by Spanish police investigating an attack plot. The Algerian suspects were detained in Madrid and Barcelona, and several large machetes and ammunition were seized. Police said some members of the cell had been known to antiterrorism police and that the arrests were carried out when they tried to buy a Kalashnikov rifle. Spanish police began Operation Arbac in December 2020 after a cell member was detected entering the country. He and two accomplices were arrested in Barcelona in January on suspicion of preparing a terrorist attack. Spanish police on Thursday said they were able to link the three to a man known as “Sheikh”, believed to be the Spanish cell’s leader. He was already known to law enforcement after being arrested in Turkey in 2016 while trying to join ISIS. After his release in Turkey, he visited countries including Malaysia, Tanzania and Algeria, allegedly recruiting members for ISIS. In March 2021, he was detected entering Spain. Surveillance allowed police to identify a group of young, highly radicalised Algerian nationals in Barcelona who were linked to Sheikh, police said.