> Why did European prices have the same increase then?

Where do Europeans get their DRAM from?

If it is the same handful of companies the US gets their DRAM from, then why would Europeans pay any less? Because the EU is not engaging in the same asinine trade war?

Sounds good in theory, but in practice those same few companies can set prices for markets outside the US to be at/near US prices. It doesn't take much effort for manufacturers to set their prices at or near those of their competitors and rely on an implicit mutually assured destruction[0] understanding.

0 - https://en.wikipedia.org/wiki/Mutual_assured_destruction

I'm sure if they didn't keep the prices somewhat similar, you would have a bunch of people in Europe selling RAM to Americans.