What does Revelation 9:17 mean?
This passage continues to describe a military whose number John heard given specifically: two hundred million. These are part of an attack levied by four angels formerly imprisoned and prepared for this very moment in history (Revelation 9:13–15).In this verse John describes the cavalrymen as wearing breastplates the color of fire, sapphire, and sulfur, roughly the equivalent of red, dark blue, and yellow. The heads of the horses resemble the heads of lions. This description compares with the description of the demonic creatures released earlier from the Abyss: "like horses prepared for battle…their teeth like lions' teeth" (Revelation 9:7–8).
The Bible often depicts horses in connection with war. Job 39:19–25 depicts the horse as mighty and brave enough to rush into battle. Verse 23 says, "Upon him rattle the quiver, the flashing spear, and the javelin."
Revelation 9:17 says fire, smoke, and sulfur proceed from the invading horses' mouths. As with the creatures of verses 7–9, some Bible teachers see in this description an allusion to modern warfare. One can imagine how a resident of the ancient middle east might try to describe a vision of a modern theatre of war. The smoke and fire of cannons, tanks, helicopters, aircraft, rifles, and helmeted soldiers would evoke dramatic imagery from such a person. If this is true, then the army John sees is very literal. Whether such interpretations are correct, it is certain that the invading army is a powerful and deadly strike force.