Defence Secretary Gavin Williamson has dismissed suggestions the UK could join a European army.
Mr Williamson told MPs NATO remained the "cornerstone" of the UK's defence strategy as he ruled out participating in any continental force.
The comments come weeks after French President Emmanuel Macron called for the creation of a "true, European army" in a bid to ensure Europe would not "become a plaything of great powers".
Mr Williamson, speaking at Defence questions in the Commons, said: "Let's make it absolutely clear: Britain is not going to be participating in a European army.
"The cornerstone of our defence in the United Kingdom on continental Europe and the North Atlantic is the North Atlantic Treaty Organisation and not the European Union."
'Security and peace'
Conservative MP Nigel Huddleston of Mid Worcestershire asked for reassurance from the Defence Secretary that the UK would continue its involvement with NATO.
He said: "NATO has been at the heart of our efforts to secure security and peace in Europe.
"As we leave the EU can he confirm we will continue to be just as keen to participate in NATO, right alongside our EU allies and friends?"
Mr Williamson said: "There's a misunderstanding that the EU is the organisation that has delivered peace and security on the continent of Europe.
"We all know that for almost 70 years now it has been NATO and he is absolutely right to point that out.
"We will continue to liaise closely with all our partners whether they are in the EU or not."