The most extreme case was the Soviet Union, and this model may still be followed in some countries: it was a separate service, on a par with the navy or ground force. In the Soviet Union this was called Voyska PVO, and had both fighter aircraft and ground-based systems. This was divided into two arms, PVO Strany, the Strategic Air defence Service responsible for Air Defence of the Homeland, created in 1941 and becoming an independent service in 1954, and PVO SV, Air Defence of the Ground Forces. Subsequently these became part of the air force and ground forces respectively
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What year did the PVO Strany become independent?
Ah, so.. 1954

One way of proving that a given disease is "infectious", is to satisfy Koch's postulates (first proposed by Robert Koch), which demands that the infectious agent be identified only in patients and not in healthy controls, and that patients who contract the agent also develop the disease. These postulates were first used in the discovery that Mycobacteria species cause tuberculosis. Koch's postulates can not be applied ethically for many human diseases because they require experimental infection of a healthy individual with a pathogen produced as a pure culture. Often, even clearly infectious diseases do not meet the infectious criteria. For example, Treponema pallidum, the causative spirochete of syphilis, cannot be cultured in vitro - however the organism can be cultured in rabbit testes. It is less clear that a pure culture comes from an animal source serving as host than it is when derived from microbes derived from plate culture. Epidemiology is another important tool used to study disease in a population. For infectious diseases it helps to determine if a disease outbreak is sporadic (occasional occurrence), endemic (regular cases often occurring in a region), epidemic (an unusually high number of cases in a region), or pandemic (a global epidemic).
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): What is no longer the causative spirochete of syphilis?
Ah, so.. unanswerable

On 25 February 1991, the Pact was declared at an end at a meeting of defense and foreign ministers from the remaining member states meeting in Hungary. On 1 July 1991, the Czechoslovak President Vaclav Havel formally declared an end to the Warsaw Treaty Organization of Friendship, Co-operation, and Mutual Assistance which had been established in 1955. The USSR itself was dissolved in December 1991.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): The Pact ended at a 1 July 1991 meeting in which country?
Ah, so..
unanswerable