Work on VTOL jets was confined to the west until Alexander Sergeyevich Yakovlev saw a demonstrator at an airshow. But the Soviet military was uninterested so Yakovlev proceed with work on his own initiative and eventually fielded the Yak 38 with the aircraft carrier Kiev. But it had limitations that made it impractical for combat. Yakovlev followed with the world's first supersonic VTOL jet, the Yak 41 which had limited deployment before it was canceled due to post cold war budget constrains.
—David Foss