Suppose that during the height of the Cold War, nuclear war unknowingly breaks out. Seemingly "on accident", by the actions of a certain group of individuals, the nuclear missiles get launched by both sides, without the agreement of the political authorities. The nuclear missiles are launched by some individuals or a group of conspirators who are not aligned with the rulers of the countries. The rulers of the countries did not want the nuclear war to start. It happened without their knowledge or approval.
But what was done was done. Several cities were destroyed, and fallout covered a significant amount of territory. But no any other military actions were taken. But the governments of these two countries have a kind of 1984 agreement with each other. They are secretly in cahoots, only making an appearance of a Cold War, and somewhere along the line someone accidentally started a nuclear war in reality.
Now that the damage has been done, the corrupt rulers are quickly scrambling to control the damage, preserve the status quo, and prevent the general public from even knowing that a nuclear war ever took place. They want to cover it up, to make sure that the general public would be uninformed of whatever happened. They want to preserve the status quo, that the fake "Cold War" is still going on, and nothing has happened.
Both of these governments are secretly working together to keep the knowledge of nuclear war from spreading. And they can use any methods to preserve the status quo. They could simply kill witnesses, kill or intimidate people who are speaking the truth, controlling the media with an iron fist, and restricting the movement of people in the country. But what would they do about the cities that got destroyed, or about the fallout over the large territories? What are some actions that they could conceivably try to cover up the nuclear war, either by claiming that aliens did it, or something else?