I don't consider the Yak-38 a copy of the Harrier. And the uniqueness of both lies only in the fact that they acheived operational service. Many other designs and prototypes existed. Both the US and the USSR realized that destruction of runways is a vital mission in wartime, and any aircraft that could operate from limited space (i.e. zero launch F-100s), would have a distinct advantage. In the 1950s the US was experimenting with VTOL, with various prototypes, including the X-14:
http://www.wpafb.af.mil/museum/fta/fta1297.htmThis aircraft accomplished its first flight on 19 February 1957. The Hawker P.1127, ultimate forebearer of the Harrier, completed it's first flight (in conventional mode) on 13 March 1961. The Yak-36 'Freehand' made it's first untethered hover on 9 January 1963. It can be assumed from these dates that development began in the late 50s. They look nothing alike:


From the Hawker spawned the Harrier line, and from the principles of the Yak-36 came the Yak-38, a streamlined, enlarged aircraft that could have at least some combat utility. There is some credence to what the Russians said regarding their space shuttle 'Buran': given a set problem, and similar technical knowledge, and perhaps a peak at what the "other side" is doing, the answers will probably bear a resemblance. This is certainly true of the heavy airlifters, as the C-5, An-124, An-22, Il-76, C-141, and C-17 all bear similarities: high wing, 4 engine transports, the largest two of which have nose doors.
Zephyr