It was meant to act as a deterrent but instead, a new NATO missile defence shield is stirring up tensions that have not been seen since the end of the Cold War.
US President Barack Obama has expressed concern about what he calls Russia's "growing aggressive" military presence. And Russian President Vladimir Putin says NATO's missile defence system is not protecting Europe, it is threatening its peace.
Poland broke ground on the northern wing of the NATO shield on Friday, a day after the defence system's first base was activated in Romania.
NATO says the sites will help protect the United States and Europe from what it calls "rogue states" in the Middle East.
But Russia insists the project is a threat to its security.
So, will this lead to a new arms race? And what will it mean for Europe's security?
Presenter: Folly Bah Thibault
Ted Seay - Senior Policy Consultant at the British American Security Information Council.
Sergei Markov - Director of the Institute for Political Studies and a former member of the Russian Parliament.
Marko Mihkelson - Chairman of the Defence Committee of the Estonian Parliament.
Source: Al Jazeera