Any assault on a Nato country would be met with a "collective and robust reaction", said its chief Jens Stoltenberg, after Donald Trump threatened to encourage Russia to attack countries that have not contributed enough to the Western military alliance.
"Any suggestion that allies will not defend each other undermines all of our security, including that of the US, and puts American and European soldiers at increased risk," Stoltenberg said.
The secretary-general's statement came in response to Trump's comments at a campaign rally in South Carolina that he would "encourage" Russia "to do whatever the hell they want" to any European countries he deemed to be in arrears.
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Trump spent much of his time as president undermining Nato, "while strong-arming members into keeping their commitments to spend more on their own militaries", said The New York Times, with the threat that "he would not come to their aid otherwise".
In his interview with Tucker Carlson last week, Vladimir Putin said that while Russia would fight for its interests "to the end" it had no desire to expand its war in Ukraine to other countries.
But several European Nato members are stepping up preparations for Russian military action. Denmark's defence minister Troels Lund Poulsen has spoken of "new intelligence [that] indicates that Russia is rearming faster than expected and that it could attack a Nato country within three to five years", said Reuters.
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