A second woman has also been arrested on suspicion of assisting an offender.
Counter Terrorism Policing South East said in a statement: “A 29-year-old woman of no fixed abode, and two men; aged 36 and 24, both from London, were arrested on suspicion of the commission, preparation or instigation of acts of terrorism, contrary to Section 41 of the Terrorism Act 2000.
“A 41-year-old woman, of no fixed abode, was arrested on suspicion of assisting an offender.”
Police said the arrests on Thursday in Newbury, Berkshire, and in London, “are in connection with an incident in the early hours of [last] Friday during which damage was caused to two aircraft at RAF Brize Norton”.
The four people are currently held in custody while enquiries are ongoing, police added.
Palestine Action posted a video online claiming it was behind the vandalism at the Oxfordshire airbase last Friday, saying activists had damaged two military planes at the base.
The group – which focuses its campaigns on multinational arms dealers and has previously targeted corporate banks – said two activists “broke into the largest air force base in Britain and used electric scooters to swiftly manoeuvre towards the planes”.
Repurposed fire extinguishers were used to spray red paint into the turbine engines of two Airbus Voyagers, while further damage was made using crowbars.
“Red paint, symbolising Palestinian bloodshed was also sprayed across the runway and a Palestine flag was left on the scene,” a statement by the group said.
Brize Norton is the largest RAF station, with approximately 5,800 service personnel, 300 civilian staff and 1,200 contractors.
A security review was launched across the “whole defence estate” following the breach, which has been condemned as “absolutely staggering” by Ben Obese-Jecty, a Tory MP and former Army officer.
Sir Keir Starmer condemned the “act of vandalism” as “disgraceful”, adding: “Our Armed Forces represent the very best of Britain and put their lives on the line for us every day. It is our responsibility to support those who defend us.”
Home Secretary Yvette Cooper said on Monday that Palestine Action will be proscribed as a terrorist organisation following the breach at RAF Brize Norton.
She said a draft proscription order will be laid in parliament next week, and if passed, it will make it illegal to be a member of, or invite support for, Palestine Action.
Proscription can lead to prison sentences of up to 14 years for some offences, although some breaches are punishable with fines.
Read more from Sky News:
What does proscription mean?
Palestine Action supporters defiant as group faces ban
The ‘enemy within’ or non-violent protesters?
Saeed Taji Farouky, a member of the group, told Sky News the proscription was “completely irrational” and “without precedent”.
He branded it a “knee-jerk reaction from the government” because the group “was able to humiliate them and show serious flaws in the defences of the RAF base”.
