What exactly do you mean? Do you mean why Iraq invaded Kuwait? Or the US responded the way it did? Or why the air campaign caused such abject destruction among Iraqi forces?

There have been entire books written on each of these subjects. We're going to need further clarification as to what exactly you want to know before we can answer you

Saddam asserted -- whether or not in good faith is disputed -- that Kuwait was a province of Iraq, and therefore its oil belonged to him and not the Kuwaiti royal family. He also presided over political / propaganda / security system reliant upon war mobilization, and no longer had a war against the Iranians to fight. Saddam may have believed -- and whether he did, or should have, is also hotly disputed -- that the US and UK would not intervene once he established new facts on the ground (i.e., a speedy occupation).

The other half of the picture is why the US and UK wanted to intervene, and why the Soviet Union didn't try to stop that intervention. For the US and UK it mainly comes down to oil and Israel -- a stable political environment, very much including the sacrosanctness of the various royal families, was critical, and the invasion destablized it. Saddam -- gratuitously, it would seem -- deciding to extend his war into one on Israel was an absolute call to arms to the US and UK, Israel's traditionally unshakable allies. The Soviet Union had a a lot of its own problems -- Eastern Europe was lost and Communism was on its last legs at home. Also, Soviet "near abroad" geopolitics was MUCH more concerned with the Turks and the Iranians, each of whom was not exactly a fan of Saddam or expansionism.