Theresa May has been urged that Nato must be kept as main Europe defence alliance
Pro-Brexit group Veterans for Britain demanded clarity on the UK's intentions to the EU's Common Security and Defence Policy (CSDP) which sets the framework for the bloc's political and military structures and operations – feared by critics as paving the way for an EU Army.
They have been alarmed by an apparent Government hint that Britain could remain tied to CSDP initiatives, limiting our military and defence industries even after Brexit.
Foreign Office Minister Sir Alan Duncan wrote last November to the Commons' European Scrutiny Committee explaining why British ministers had agreed to certain developments in EU defence policy.
Pro-Brexit group Veterans for Britain demanded clarity on the UK's intentions to the EU's CSDP
CSDP creates bureaucratic impositions and a level of integration that we would not enter even with our closest ally, the United States
Rear-Admiral Roger Lane-Nott
Sir Alan added that "as many member states have expressed an interest in the UK continuing to play a role in CSDP after we leave the EU, we have invited other member states not to bring forward initiatives that could make such cooperation harder".
He also stressed, however, that Britain had highlighted the need for the EU not to duplicate Nato unnecessarily, for member states to retain ownership of their forces, that Brussels should never be allowed to command military operations, and for Europe's defence industry to remain "open and competitive".
Veterans for Britain said Britain after Brexit could still cooperate with the EU on issues like piracy and humanitarian rescue but must not be bound by any of its limits on our military operations and defence industries.
Rear-Admiral Roger Lane-Nott, a retired former commander of the UK submarine fleet, said: "CSDP is a rolling programme of military integration which according to the Lisbon Treaty is designed to lead to Common Defence, the EU's term for military union.
Sir Alan wrote that Britain had highlighted the need for the EU not to duplicate Nato unnecessarily
"As a result, CSDP creates bureaucratic impositions and a level of integration that we would not enter even with our closest ally, the United States.
"There is no reason why the UK as an autonomous, self-governing nation would have anything to gain from throwing away control over defence, the most significant aspect of statehood.
"A statement from ministers that an independent UK will not take orders via CSDP would focus minds at the EU Commission and force them to consider a future for Nato in which they have to respect and listen to their partners such as the UK and US."
Veterans for Britain were also angered this weekend when EU chief Jean-Claude Juncker, speaking at a security summit in Munich, attacked US President Donald Trump's call for European Nato members to spend more on defence.
Col Richard Kemp, a former commander of British forces in Afghanistan, said: "These irresponsible comments simply encourage more delinquent behaviour by European governments on defence. Many EU member states are freeloading on the US, UK and other countries which do pay their way in the Nato alliance.
11 things you need to know about NATO
Tue, February 14, 2017
NATO – The North Atlantic Treaty Organization is an intergovernmental military alliance based on the North Atlantic Treaty which was signed on 4th April 1949. The organization constitutes a system of collective defence whereby its member states agree to mutual defence in response to an attack by any external party.
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Every member country, no matter how large or small, has an equal say in discussions and decisions. Photo shows: Signing the North Atlantic Treaty which marked the beginning of NATO, 1949.
"It is extraordinary that the lead architect of EU Defence Union would resist a perfectly reasonable US request for members of the alliance to respect their duties."
A Government spokesperson said: "We are leaving the EU but cooperation on security with our European and global allies will be undiminished.
"All of us in Europe face the challenge of cross-border crime, a deadly terrorist threat, and the dangers presented by hostile states. With the threats to our common security becoming more serious, our response cannot be to cooperate with one another less, but to work together more.
"Our future relationship with the European Union will include practical arrangements on matters of law enforcement and the sharing of intelligence material with our EU allies.
"We will do what is necessary to keep our people safe."