The description of the invasion as a flood, continues. The king of Assyria, or now we need to refer to Assyria as the invading army from the north, because this invasion serves a dual purpose.
First, Assyria will indeed invade. Second, the prophecy also applies to the Tribulation when an even greater army and invasion will occur igniting the Armageddon campaign.
But the whole purpose of this verse is to assure all of the believers in history, that despite the plans that the world has for the Middle East, the nation of Israel, and of Judah, this region still belongs to God and it is His plan that will succeed, not mans.
And so Assyria will invade as a flood. Its reach will be vast as the wings of a bird covers all of the land. Not a single part of the land will be left untouched.
The neck of the country is compared to the head of a person, for indeed it will be people that will be affected. But, when a flood overcomes a person up to their neck in water, then they are indeed in trouble. And so the land, the entire country will be overwhelmed to the very brink of total destruction.
Jerusalem is a city that is the capital, and represents the pinnacle or the head of Gods plan. To overwhelm that nation to the neck of the land, indicates the massive magnitude of the invasion, but at the neck it stops and goes no further.
The invasion is coming, and it is coming because the people refuse to see the truth of their errors and their rejection of God. But, even the massive invasion that will be brought by Assyria, and the massive invasion that will occur in the future in the Tribulation, will not prevent Gods plan from succeeding.
This ancient invasion will be vast, but it will not cancel or end Gods plan for the Messiah, will not end the reign of Davids line, will not end the nation of Judah.
Likewise in the future Tribulation, where the invasion will take on even greater atrocities and proportions, Gods plan for humanity, for believers, for the deliverance of those believers who will live in that future time, will not be defeated. The Second Advent will occur and evil will be defeated in the blink of an eye.
Therefore, the promise of God. His plan will succeed and will become a reality regardless of the massive attempts of humanity to destroy it by whatever means.
Attempts by Syria and Samaria failed. Attempts by Assyria and Babylon and Persia and Greece and Rome failed. And attempts by the future empire of Satan will fail. With each succeeding invasion, will come greater and greater destruction, but Gods plan will not and cannot be defeated.
Likewise, in your individual life, God has a plan for you. You may have to live many years before you see it or are faced with your ultimate tests, but if you stay with your daily study, grow up in your spiritual life and build up your faith, then hopefully you will realize that God has your best interest at heart, in His plan.
End of study