Yeah, the US, which doesn't even want to put boots on the ground regarding Iran, will totally start invading nuclear powers in Europe any time now. Totally.

The US political system is inherently unstable. It has a strong god-king executive branch of government, and only uses first-past-the-post voting, which results in truly insane election results, and little to no need for cross-party coalition building.

Germany has a partially proportionate-representation multi-party strong-parliament system. While some fringe lunatics can definitely win an election, they are incredibly unlikely to sweep it.