The book of Nahum is a collection of poems announcing the downfall of Assyria, one of Israel's worst oppressors. Referencing Daniel, Exodus, Isaiah and Babylon, Nahum shows us that the destruction of Nineveh and Assyria are examples of how God works in history in every age.
He is committed to justice and will not allow any arrogant, violent or evil nation to endure forever. However, while He defeats evil, He is also good and cares for the innocent. He will provide a refuge on the day of distress for anyone who humbles himself before God, believes in God's justice and trusts that in His time He will bring down oppressors in every time and place.