Why did Clinton laugh at Yeltsin?

Cultural understanding is wrong.

Cultural differences and interpreter translations caused Bill Clinton to misunderstand the content of Yeltsin's speech.

What Yeltsin really means is: Before I met with Clinton, you predicted that our meeting would fail. But now I tell you, and this is not the first time I have told you that you failed. Our meeting had a positive outcome, with Yeltsin's translator translating Yeltsin's words into Well, now for the first time I can tell you, you are a disaster.