In the mid-1940s the US had beaten its rivals, notably the USSR and Nazi Germany, in developing the atomic bomb. This weapon of extreme power and potency fundamentally changed politics and warfare from that point onwards. However, for the four years before the Soviet Union created its first weapon the US had true unipolar power to use this new weapon as it saw fit with no fear of similar reprisals from its enemies. This is perhaps best exemplified by the bombings of Hiroshima and Nagasaki in 1945. This use of mass-destruction weapons on civilian populations has caused huge controversy, but arguably shortened WWII and lessened the loss of life that would have been caused by a ground invasion of mainland Japan. However, from the point of this article, the more important thing about the bombing of Japan is the ability of the US to carry it out. Unlike the Mutually Assured Destruction present during the Cold War, America could carry out this paradigm-shifting attack with impunity knowing that no other state could respond in kind. The unipolar ability possessed by the USA in 1945 obviously failed when the Soviets developed its own bomb. 67 years later nuclear arms are definitely owned by the USA, UK, France, Russia, China, Israel, Pakistan and India and were given up by South Africa. Multi-polarity, both globally and regionally is now the natural state of the political environment.
However, we may now be living in the next technological unipolar moment. While the possession of Unmanned Arial Vehicles (UAVs) is spreading, it is currently being led by the USA and it's allies including the UK and Israel. Other states including Russia, China and Iran have started developing their own systems though with varied success or prospects. This situation, similar to the early Cold War has led, indeed, to similar results. The US now dominates the field and have deployed UAVs to Turkey, the Seychelles, Djibouti, Pakistan, Afghanistan, the Philippines, Somalia and Yemen to combat terrorist groups such as Al Qaeda, AQAP, AQIM, Al Shabaab and the PKK. With relative impunity the US has used this power to strike anybody or location they deem to be connected to terrorism. They have declared it legal, they have chosen the target and nobody, not their targets, opposed states or the UN, have the ability to stop them doing so. While the development of similar UAV and UCAV systems by American rivals, notably China and Russia, will deplete America's ability to use their drones at will the inability of weak states and the terrorist groups being targeted will mean that the advantages of these unmanned systems will still be huge.
Israel is yet another demonstration of the unipolar power of UAVs, if a regional one. Apart from allied US drones in Turkey, Israel possesses the only viable UAV fleet in the region. This small state has always striven to use technology as a means to combat the human and resource advantages of its neighbouring enemies. By developing strong air forces, intelligence structures and technological aids for its troops Israel has managed to beat coalitions formed from Egypt, Syria, Jordan and Lebanon. UAVs represent the new way to give a small, technologically advanced state the edge when fighting with much larger, less developed rivals. Larger systems, like the US's huge Global Hawk, may also allow the US to gather intelligence and strike individuals and targets in states such as Iran which do not border Israel which is sure to be a bonus for the Israeli Defence Force (IDF) and the MOSSAD.
Just as nuclear weapons proliferated to all sides and regional conflicts within the Cold War, the early technological unipolarity of America allowed it to attack Japan in 1945 with complete impunity. Similarly, UAVs are proliferating as the US's rivals' attempt to match its lead. However, especially in the GWOT, America (and its allies) hold a monopoly on the mass use of drones allowing them to target as they will across vast swathes of the Middle East and North Africa without any ability for anyone to stop them.