2 Kings 25:1
And it came to pass in the ninth year of his reign, in the tenth month, in the tenth day of the month, that Nebuchadnezzar king of Babylon came, he, and all his host, against Jerusalem, and pitched against it; and they built forts against it round about.
In the ninth year of Zedekiah's reign, Nebuchadnezzar, king of Babylon, came against Jerusalem with his whole army. He pitched against the city and built forts round about it, thus beginning its encirclement and siege. That encirclement was the formal start of the siege operation against Jerusalem.
The siege marked the start of a hopeless outlook for Judah. It brought the Lord's judgment upon the city, with fear and defeat to follow. This coming judgment with its fear and defeat is what Ezekiel's prophecies describe.