Only a signal

Various plans existed for the demonstrative use of a nuclear weapon against Soviet targets to signal that the United States, or NATO, was prepared to use the weapons. The Germans did not wish for the demonstration to take place on German soil. And several of the allies, led by the Canadians, were anxious the Soviets would not understand that the use of nuclear weapons was only a signal, and feared that
such a use would touch off a nuclear holocaust.

…

By attempting to use NATO as a component of American strategy … the United States had opened up the one question NATO had studiously sought to avoid: How—and why—would NATO go to war?

NATO military plans, since their earliest incarnation, rested on the premise of defense against a Soviet attack. Now, however, the Americans‘ plans considered using military force not in defense but as „gambits in a psychological contest against the enemy.“ Military force, though couched in the language of last resort by the Americans, did not mean a last resort before Western Europe was overrun by Soviet armor but the last resort to keep open access to Berlin.

These plans made interpreting article 5 of the North Atlantic Treaty—especially the definition of an „armed attack“ on an ally—more difficult. „When,“ Stikker asked, „does it cease to be an attack and instead the consequence of a miscalculation on the part of some individual country, a miscalculation for which the other members cannot be held responsible?“

—Timothy A. Sayle, Enduring Alliance, (Ithaca, NY: Cornell University Press, 2019), 96.