Armenian is an Indo-European language spoken in the Caucasus.
By Thomas V. Gamkrelidze and V. V. Ivanov Scientific American, March 1990, P.110
This inference is supported by what is known about the portion of the Indo-European community that remained after the Anatolian family had broken away. From that community came the languages that persisted into written history. The first to branch off was the Greek-Armenian-Indo-lranian language community. It must have begun to do so in the fourth millennium B.C. because by the middle of the third millennium B.C. the community was already dividing into two groups, namely, the Indo-lranian and the Greek-Armenian. Tablets in the Hattusas archives show that by the middle of the second millennium B.C. the Indo-lranian group had given rise to a language spoken in the Mitanni kingdom on the southeast frontier of Anatolia that was already different from ancient Indian (commonly called Sanskrit) and ancient Iranian. Cretan Mycenaean texts from the same eras as Mitanni, deciphered in the early 1950's by the British scholars Michael G. F. Ventris and John Chadwick, fumed out to be in a previously unknown dialect of Greek. All these languages had gone their separate ways from Armenian.