Unrestricted warfare is when two countries go to war but don't just fight with soldiers and weapons, they fight by using whatever means necessary. This could mean anything from cyber attacks to economic sabotage. It's like two countries are in a competition to outsmart each other and try to come up with ways to cause problems for their enemy. The idea is to show the enemy who is the strongest and who has the best plan. Everything from money to technology to ideas can be used in unrestricted warfare.