There is no case of they just needed to pay attention earlier. The problem is known. There is just no good solution. Drastically scaling back energy consumption isn't going to happen any time soon and would harm the economy. So we can choose between Russia, the Middle East and the USA. Best would be of course to reduce fossil use, but that is orthogonal.
Refraining from shutting down their nuclear plants for no good reason would have been a start.
Trump is completely inconsistent anyway. First he blamed the EU for wanting to continue the Ukraine war. Then he periodically floats lifting Russia sanctions. But if the EU were to lift Russia sanctions, that of course would lead to severe repercussions.
Trump is about economic suppression of the EU.
If you say "nuclear energy". The US has imported Russian uranium to at least 2025.