In a joint press conference, given in Tallinn with the US President Barack Obama, Ilves indicated that there might be a way around the NATO-Russia Founding Act, according to which the alliance is not supposed to set up military bases near Russian borders.

"The NATO-Russia Founding Act has been violated by Russia. We continue to support the vision of that document, but its substance has changed dramatically," the Estonian President said.

President Obama avoided giving a straightforward response on the subject, but he conceded that the security environment of 2014 is not the same as in 1997, when the then Russian President Boris Yeltsin signed the pact.

"The circumstances have clearly changed and this will be a topic for discussion in NATO summit in Wales," Obama said.