I agree this obviously goes beyond Trump. My view is that this is primarily about preventing Eurasian integration. The biggest problem the US has is that it sees China as its main geopolitical rival, and needs to refocus resources away from Europe. However, if the US simply left, then Europe would start becoming economically integrated with the east by necessity, and that would necessarily translate to a geopolitical realignment. The conflict with Russia provides a solution to this problem. Europe is now forced to devote its resources towards filling the gap the US is leaving in NATO, while Russia is similarly forced to devote increased resources towards military spending. The hostility between Europe and Russia also means that any serious economic integration of Eurasia is significantly delayed. Although Europe continues to build economic relations with China, there is an atmosphere of distrust, and Europe ultimately sees China as being aligned with Russia. Thus, the trade relations between them are tepid at best.

To sum up, I think that increased military spending is a way to keep Europe down and tie up Russia while the US pivots to attempt and contain China.