Isaiah 18:3-4. “All ye inhabitants of the world, and dwellers on the earth, see ye, when He lifteth up an ensign on the mountains; and when He bloweth a trumpet, hear ye. For so the Lord said unto me, I will take my rest, and I will consider in my dwelling place like a clear heat upon herbs, and like a cloud of dew in the heat of harvest.”
All the people on the earth, not just Israel, will see when God lifts up an ensign (emblem, banner, flag). The only One He is predicted to lift up is Messiah, Jesus Christ, so we can properly place this passage in the end times. Many will not rally to Christ, being under the control of the Antichrist (Zech.14; Rev. 16:12-16; 19:11-21).
Jehovah will blow a trumpet at this second advent of Christ ((Joel 2:1; Zech.9:14). All people on earth will hear that trumpet, and none will doubt that its sound is from God.
God will bide His time, waiting until all prophecies up to that point have been fulfilled, waiting until the harvest is ripe and ready.