Eight people have been arrested at Prestwick Airport after protesters boarded a plane.
Police have arrested a total of 12 people at Prestwick
A spokesman for campaign group Trident Ploughshares told BBC Scotland three people had managed to get onto a US military personnel carrier.
He said they were searching for evidence to suggest the plane was carrying bombs to Israel.
On Sunday, four people were arrested after demonstrators broke through security fencing onto the main runway.
It was reported last week that US military flights carrying bombs to Israel would no longer use any civilian airports in the UK for refuelling.
The protesters describe themselves as "citizen weapons inspectors" and said they were searching for evidence to suggest the plane was en-route to Israel carrying bunker busting bombs.
Trident Ploughshares said seven people got through security fencing at the airport and got into the freight area, with three managing to get on board a US plane.
It is claimed one of the protesters was sitting in the pilot's seat reading a manual when he was arrested.
Strathclyde Police said seven people had been arrested at the airport on Monday morning and confirmed a number of protesters had been on board a plane.
A 65-year-old woman was arrested later on Tuesday bringing the total number to eight.
'Full security review'
Assistant Chief Constable Ian Learmonth said: "These alleged breaches are of concern and further talks were held today between myself and representatives of the airport.
"We have asked that they undertake a full security review and we will support them by providing expert help."
A spokesman for the airport said: "Glasgow Prestwick Airport is investigating the incidents, as are the authorities, and additional security resources have been in place since we became aware of a similar incident on Sunday morning which led to four arrests.
"We are satisfied that our security measures are working effectively as these people were apprehended very quickly.
"Aviation security is tighter than that of most other industries and security at Glasgow Prestwick Airport is consistent with the measures in place at other major airports in the UK."
A 25-year-old man and three women aged 36, 45 and 52 were arrested at 0045 BST on Sunday.
Three women aged 48, 55 and 68-years-old and four men aged 25, 46, 50 and 56-years-old were arrested at 0330 BST on Monday.
All are expected to appear at Ayr Sheriff Court on Tuesday.
John Scott, Conservative MSP for Ayr, said he was extremely concerned about the lack of security at the airport.
He said: "This is a matter of the greatest concern for the safety of the airport.
"I don't think protesters are going about this the right way. I share their concerns this ordnance may have been going through this airport.
"I believe that ordnance has stopped going through this airport.
"I am concerned that the protesters are putting users of the airport at risk, the passengers, the staff and, indeed, themselves."