The United States Army.
The US Empire and its Imperialistic Military policy.
No. The Air Force is one of the most powerful military branch in the World. No other military branches has ever defeated the Air Force branch.
Luck and willpower.
The emergence of a powerful Soviet Union
The Roman military was the most powerful force the world had seen (up to its time). It stood out from the other contemporary fighting forces because of its superior training, equipment, and speed/ease of movement.
Yes, although the Chinese have the most numerous military in the world. Our Air Force, Army, Coast Guard, Marines and Navy have a capability that is known to be extremely powerful and probably have the military ability to do stuff that is top secret.
It was the newest technology, and the navy was the most powerful force in the military.
This is the Turkish military, fourth largest military force in the World.
In the second century it was the Roman force that was powerful both in their military strength and politically as well.
Janissary Corps
Offcourse,India is the third most powerful nation by military and fourth in naval power.
If any nation were to attempt to attack the US, the Air Force would provide a very powerful defense. When the US engages in various military actions, as it has recently in Iraq, Afghanistan, Libya, etc., the Air Force is capable of inflicting enormous damage on the enemy. It is the most powerful air force in the world.