Russia is looking to reestablish its Soviet borders, with a focus on Europe. Belarus is a Russian puppet, but Ukraine can go either way and Ukrainian territory is strategically important to Russia. Beyond that, Russia would probably want to bring in the Baltic nations as well, which is probably what intelligence agencies refer to as Russia wanting to attack Europe.
Beyond reforming the old empire, Russia wants to establish a greater sphere of influence in Europe and weaken potential rivals. A united EU is a threat in that can provide a unified response to Russian expansion.
The USA under Trump wants to make being an empire worth it financially while getting some territorial gains.
Greenland could be a second Alaska for the USA as Greenland has untapped mineral reserves and a strategic location in the Arctic Circle. Annexing Canada would be on par with the Louisiana Purchase or gains from the Mexican-American War. Panama is a major strategic asset.
Trump wants to leave Europe because he doesn't see anything for him by staying.