Seven people have been arrested on suspicion of aggravated burglary at a factory in Kent.
Protest group Palestine Action said members had targeted the Instro Precision factory at Discovery Park, Sandwich.
The group said the company is a wholly-owned subsidiary of Israel’s largest weapons company, Elbit Systems.
Instro Precision said it would work with the authorities to “prosecute any person or group threatening the safety of our staff or their important work”.
A company spokesperson said: “This facility is designed to meet the requirements of the UK armed forces and in particular support the British Army with a range of state-of-the-art electro optics and night vision systems.
“It is highly irresponsible to sabotage this work, particularly during a period of global instability.”
Palestine Action said some campaigners had used rolls of spikes called stingers to stop vehicles getting into the site while the break-in took place.
Kent Police said officers were called to a report of a protest at shortly before 03:30 BST on Monday.
A spokesperson said officers were at the scene and those arrested had been taken into custody.
The group also claimed to have targeted the Scotiabank building in Bishopsgate in the City of London.
The building was sprayed with red paint and activists blocked doors at around 6am on Monday.
Detective Chief Inspector Paul Doyle said 10 people had been arrested.
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