In Nahum 2:3–5, Nahum’s vision of the pending attack on Nineveh develops as he now sees the attacking army approaching the walls of the city. Visions such as this, of a powerful invading force, are also seen in other prophetic writings.1
The approaching army that Nahum sees is simply described as his mighty men.
Nahum is seeing the Babylonian commander leading his mighty army. But, as throughout the book, the reader is left in no doubt that it is the Lord himself who is bringing this invasion.
3 The shield of his mighty men is red; his soldiers are clothed in scarlet. The chariots come with flashing metal on the day he musters them; the cypress spears are brandished.