Forcing with mate threats
If a chess player overlooks a mate threat, it’s game over. That’s why mate threats make strong forcing moves. Very often, the only way to defend against a mate threat is by giving up material.
In the example, Black can win the white rook by first threatening mate with his own king.
Mate threats are less forcing than checks. Your opponent might decide to react with a counterattack against your king. Always be aware of that possibility.
What do you have to do?
Win material by a mate threat.