How can God be charge when some rulers are such tyrants?

The king's heart is like a stream of water directed by the Lord; he turns it wherever he pleases.
Proverbs 21:1 NLT

God's authority
God rules his creation. Nothing is outside his authority—not even the leaders of the nations and kingdoms of this world. No person is placed in a position of power outside of God's will. This can be a great comfort when we see leaders take over in various places, especially leaders with whom we do not agree.
So what does this mean for the cruel tyrants of the world?
It means that they too are under God's authority. Satan may author their evil acts, but their wrongdoing can only occur within the boundaries God sets. Why those boundaries are where they are for some nations is a question only God can answer. But we can rest assured that no power is in authority outside of God's plan. God always accomplishes his will, even through the most wicked leaders. God is always the final authority.

WISE WAYS
How will you pray today for the leaders of your country, as well as for leaders around the world?
Today, Lord, may I trust that you are the sovereign authority over all that happens in my nation. May I trust you, even as I work on your behalf.

adapted from The One Year® Book of Proverbs by Neil S. Wilson, Tyndale House Publishers (2002), entry for February 21