He stressed that the fight against international terrorism and anti-Semitism "must be a collective effort of the international community".

BBC: NEWS | Europe | World leaders denounce bombings

But our collective security is not just about the economy, or crime, or terrorism.

BBC: NEWS | UK | UK Politics | In full: Cameron speech

In short, it is increasingly clear that the danger of nuclear terrorism is one of the greatest threats to global security -- to our collective security.

WHITEHOUSE: President Obama at Opening Plenary of Nuclear Security Summit | The White House