The Assyrian Encyclopedia

The Assyrian in Prophecy. The Spirit of God in the Old Testament used the political circumstances of Israel as a pattern of future coming events. Prophecy was given to warn Israel about the events that would shortly take place in the near-term, but much of the details look on to a future, final fulfillment. Two great historical events were used by the Spirit of God as a backdrop for the prophets; the aggression of Assyria and the aggression of Babylon. Isaiah, Hosea, Amos and Micah were written during the time of the Assyrian aggression, and the title "the Assyrian" is often employed to describe the apocalyptic enemies of Israel in those prophets.
Two Attacks. Historically, Assyria made two great attacks on Israel. First, Shalmaneser king of Assyria swept down and successfully took the Northern Kingdom of Israel captive. Second, Sennacherib king of Assyria swept down ten years later and unsuccessfully tried to take the Southern Kingdom of Judah in the days of Hezekiah. These two attacks, ten years apart, are used as the pattern for two great apocalyptic attacks on Israel.
The first apocalyptic attack. The first attack of the Assyrian is carried out by the King of the North and his Arab Confederacy. Like the historical attack of Shalmaneser, the King of the North will successfully enter and pass through the land of Israel, wreaking havoc along the way. This first attack is called "the consumption" (Isa. 10:22; 28:22; Dan. 9:27). This attack will utterly devastate the land of Israel, it will be the judgment of God on the apostate Jews in the land. The King of the North will continue south into Egypt, and later return, where he will be met by the Lord and destroyed. 
The second apocalyptic attack. The second attack of the Assyrian is carried out by Gog and Magog, the King of Russia. While the first attack will take place before the appearing of Christ, the second attack will take place after the appearing, when Israel is at rest in their land. Gog will come down "from the uttermost parts of the north" with "many nations" in her confederacy, in an attempt to overthrow restored Israel (Ezek. 38-39; Isa. 10:28-32; Mic. 4:11-12; 5:5). The Lord will "roar out of Zion" (Joel 3:16) and defeat this army before they can enter the city. Read more...
Summary. We have seen that both the Russian Confederacy and the Arab Confederacy act at different times under the title “the Assyrian”. Furthermore, they are called in Rev. 16 “the Kings from the East”. Their advances may be referred to as “the first and second attacks of the Assyrian”. Together, the King of the North and the King of Gog (Russia) compose "the Assyrian".