> The US and France are both nuclear armed, including nuclear armed submarines, which are the ultimate defence deterrent.

Except for France's ASMP-A nuclear warning shot (which is not a tactical option by the way), all other independent European nuclear options (French or British SSBNs) are not only strategic, but they imply wiping entire countries off the map. All options also depend on whether the French President or the British Prime Minister decides that this course of action is warranted.

If Trump indeed invades Greenland, shoving a French-made nuclear fireball in front of an American carrier battle group off the coast of Greenland would probably not be our first option. Besides the massive political cost of breaking the nuclear taboo, if kinetic actions are deemed necessary, deterrent also comes in conventional varieties.

Also, while the British nuclear deterrent might be operationally independent, it relies on American-supplied Trident missiles.