It was under these politics of world conquest that WW1 and WW2 were fought upon. All countries... US included, fell into the trap of imperialism. Expanding during the Spanish American war, gaining the Philippines, Guam and other territories.
The current world has no apatite for imperialism, although I guess this can change quickly. But... knock on wood... lets hope the great powers of the world continue to refuse a direct fight with each other. The worst we have between great powers today are some economic rivalries.