The early stalemate on the Turkish border and the period of rapid maneuver warfare that followed it had once again devolved into stalemate by mid-August, 1942; the Soviet forces could not cross the Bosphorous without transport elements of the Baltic Sea Fleet, which was trapped in Leningrad by the surprise American declaration of war. While his air marshals settled in for a long bombing campaign against the Turks in Istanbul, Stalin's eye turned eastward.
Persia had long been a Soviet target; not only did it possess reserves of oil the Soviets did not want falling into Allied hands, it contained the port of Bandar Abbas at the mouth of the Persian Gulf, a crucial fueling and supply stop for Soviet vessels transiting between Europe and the Pacific. There were few obstacles between the Soviets and the capture of Persia; the latter's military was weak and badly deployed, and once the Soviet armored spearhead crossed through the mountainous regions surrounding Tabriz and reached the Gulf coast, the war would be over in a matter of weeks. Twenty divisions under Zhukov and Bagramian positioned themselves on the Persian border, and on the 21st of September, war was declared.
Meanwhile, Soviet researchers had not been idle. In early September, engineers conducted the final tests of the first practical turbojet engine. It was only a matter of time before Soviet airframe design caught up. At the same time, the faculty of the Frunze Military Academy laid down major changes in overall Soviet doctrine, solidifying the procedures of Deep Operations that had, in less explicit form, guided the Soviet Armed Forces since the mid-1930s. Nikolai Kuznetsov began a similar project soon after, codifying Soviet naval tactics.
The war with Persia began with an attack by six infantry divisions into the Rasht region, opposed by one Persian division which fled after taking five hundred casualties, though not before inflicting the same number on the advancing Soviet forces. The main armored thrust targeted Tabriz, but was greatly slowed by roads worse than anticipated. Zhukov's army group would spend nearly half of the time it required for the operation bogged down in northern Persia.
Soon after war was declared, two Persian divisions advanced into the Soviet Central Military District, opposed by the only two divisions present there plus a corps of four obsolete Tannu Tuvan divisions on temporary loan. Persian forces made initial gains before the Soviet and allied defenders arrived only in early October. Four days after arriving in Bukhara, however, they had turned the fight around and were chasing the Persians off of Soviet soil.
The war in Persia was destined to become little more than a footnote, however; on the 18th of October, 1942, elements of the United States Marine Corps landed in the Far Eastern Military District, carried through the Sea of Japan from the Philippines; more would arrive over the course of the next week. Caught off-guard, the Soviets had only a handful of older troops protecting Vladivostok, and by the 20th, the US Marines had surrounded the city. Five Soviet infantry divisions and a handful of air wings, supplied by the merest trickle of transports from the ports north of the American invasion, faced off against five divisions of Marines, with more on the way. The Siege of Vladivostok had begun.