Sometime in the late 1940s or even in 1950, while he was President of Columbia University, General later President Eisenhower developed his "tripwire" theory which became, de facto, Western doctrine. Ike said, in a letter, I think, to someone in the Truman administration but which was widely circulated, including to Louis St Laurent, that he expected the Soviets to deploy millions of men on the inner-German border to threaten the West. The natural response, he said would be to want to deploy almost as many Western soldiers there to face them down.
That response, Eisenhower said, would be wrong. The best place for millions of young Western men, he opined, was at home: growing crops, building homes and roads and cars and refrigerators and washing machines. That he suggested, not standing "nose-to-nose" against the Russians is how the US-led West would win.
What was needed in Europe, Ike, said, was a tripwire force ~ a smallish force of professional, regular soldiers who could fight a mobile defence in depth (I'm not sure he used those words, I think they come later) which would be only one part of a full response that would include tactical and, if necessary, strategic nuclear weapons. (Remember, please, that this was before the first H-bomb was tested (1952), before the first B-52 was delivered (1955) and before the first ICBMs flew (1957). The difference between strategic and tactical nukes was not huge, the real difference was the nature of the targets. Ike probably intended to bomb the second echelon forces while they were forming up.) This idea formed the basis of what I believe is still NATO's policy which is NOT to agree to "no first use." Ike disliked nuclear weapons and he hated the idea that America had been the first country to use them but he understood their value and he was, always, morally willing to use them again to save Western lives.
Ralph Bunche, Mike Pearson and Brian Urquhart used the same tripwire notion in 1957 when they proposed a large, lightly armed UN peacekeeping force in the Middle East to separate Israel and Egypt ~ it was significantly different from the previous (late 1940s) peacekeeping "observer" missions on India's and Israel's borders.
It seems to me that what Secretary General Stoltenberg is proposing is that tripwire, yet again. The notion is that the tripwire doesn't have to be huge ~ just big enough to put up a credible fight because it is backed up by a nuclear arsenal that America and Britain are able and willing to use.
(I believe it was that letter, as much or even more than anything else, which persuaded St Laurent to ignore Grant (CNS), Foulkes and Simonds (CGS) and tell Brooke Claxton to press ahead with his plan to "professionalize" the Canadian Armed Forces even as the global strategic situation was nearly falling out of control.)
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Edited to add: The tripwire idea may have been Gen George Marshall's, I'm not sure. The references I have seen credit Eisenhower but it is generally accepted that Ike didn't say or write much that wasn't, at least blessed if not originated by Marshall.