The “collective weight” of partnerships such as the EU made it easier to deal with global threats, he told the BBC.
David Cameron will face MPs later as he presents his case for the UK remaining within the 28-member organisation.
But Mayor of London Boris Johnson has again insisted that the country has a “great future” outside the EU.
Mr Johnson’s declaration on Sunday that he backs EU exit is being seen as a significant blow to Mr Cameron’s campaign to remain in the EU.
The prime minister will outline details to MPs in a Commons statement, starting at 15.30 GMT, of last week’s deal with EU leaders on reforms to the terms of the UK’s membership, which paved the way for him to call a referendum on EU membership on 23 June.
He says the deal strengthens British sovereignty and the UK will be “safer and stronger” remaining in the EU.
Big partnerships’
This message was echoed by Mr Fallon, who told Radio 4’s Today that the UK benefited from being part of international partnerships, such as the European Union, Nato and the United Nations.
He rejected claims by former Conservative leader Iain Duncan Smith, one of six Cabinet ministers campaigning for the UK to leave the EU, that the UK’s membership actually exposed it to greater security risks, pointing out that the EU had taken the lead in confronting Russia over its annexation of Crimea and Iran over its nuclear programme.
http://www.bbc.com/news/uk-politics-eu-referendum-35628051
#AllTheNews 