Petition That Parliament should not agree to the UK being part of an EU defence force.
President of the Commission said that the EU is moving to having a single defence force. To avoid UK forces being committed to such a military force under EU law, Brexit agreement should contain clear legal drafting that excludes any such possibility.
http://www.bbc.co.uk/news/world-europe-31796337 contains a report on the Presidents' policy by the BBC. The joint statement between the President and the Prime Minister of 16th October mentions security co-operation between the UK and the EU in the context of what happens after Brexit.
At 10,000 signatures...
At 10,000 signatures, government will respond to this petition
At 100,000 signatures...
At 100,000 signatures, this petition will be considered for debate in Parliament