During october of 1973 a coalition of Arab states led by Egypt and Syria start an attack towards Israel during the holiest day in Judaism religion, the Yom Kippur. The objective of the Arab coalition was to take back Sinai and the Golan that were lost in the 1967 Six-Day War against Israel. Another objective of Egypt was to seize a foothold on the east bank of the Suez Canal and use it to negotiate the return of the rest of Sinai.
United States and the Soviet Union initiated massive resuply efforts to their respectives allies during the war leading to a near confrontation between the two countries.
Israel began receiving supplies via U.S. airforce airplanes on October 14, the war iniciated on October 6. After some debates on U.S. soil about helping or not the Israel army the president Richard Nixon finally decided to send supplies because Israel´s army was overwhelmed and they were thinking to "go nuclear" according to the Secretary of State Kissinger.
The arab coalition receive the aid of the Soviet Union in two different ways; first they sent supplies to Syria and Egypt by air and sea and second, specially on the Golan front the Syrian forces received direct support for Soviets technicians and military personnel. At the beggining of the war ther were about 2000 soviets troops serving in the Syrian army. The technicians repaired the damaged equipment from the Syrians and retrieved abandoned Israeli military equipment for shipment to Moscow. There were even some Soviet military personnel that went into battle with the Syrians nad approximately 20 Soviets soldiers were killed in action.
To sum up the answer we can say that U.S. army supported Israel by sending supplies and the Soviet Union army supported Egypt and Syria by also sending supplies and taking a minor participation in the war.
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