Europe needs to acquire a nuclear arsenal that stands head-to-head with the Russian one quantitatively and independent from the U.S. or any other nation (including the French and British) for nuclear deterrence. This means many more European nations need to acquire a nuclear arsenal.
The frustrating part is that the U.S. doesn't want to give assurances whether it will come to Europe's aid if it were attacked, but at the same time doesn't want European nations to develop an independent nuclear capability. Many European nations (Poland, Finland, Sweden, Germany) are currently contemplating going nuclear. The U.S. is actively discouraging them to do so.
Reputation is a fickle thing, so difficult to build, and so easy to lose.