In end time prophecy specific nations are key players. The main nation is Israel. The next is the European Union. Israel formed in 1948 while the EU formed three years later. The European Union is the final world empire forecast by the Prophets. This empire will launch the Antichrist.
At Prophecy Talk you will find information on the nations that are key players in end time prophecy.
It should be noted that the United States is not a key player during the Tribulation. The US is included because of speculation on its decline as a world power, which leads to the Tribulation. In addition, decisions that the US is making are helping to pave the way for predictions in the Revelation.
For the various nations in prophecy see the pages below.