I believe it'll be different with the United States. You might not believe me, but this is what I think: God let empires rise and fall throughout history, and in the latter days, a new kingdom will come forth as a stone without hands that will eventually fill the earth (See Daniel 2:36-44). I believe this stone represents The Church of Jesus Christ of Latter-day Saints, but the US was established by God to allow religious freedom so that the church can be established and grow to fill the earth before the Second Coming.