What to answer to peoples saying USA offensive against iraq for "invading kuwait" was justified ?

The US turned Iraq's infrastructure into a smoldering crater. It took until around 2008 for Iraqi power generation to return to pre Gulf War levels. The US used depleted uranium rounds extensively, which has a high probability of causing the increased birth defects and cancer rates Iraq is and has been experiencing.

hell, just send them this

"Many of the targets were chosen only secondarily to contribute to the military defeat of [Iraq] ... Military planners hoped the bombing would amplify the economic and psychological impact of international sanctions on Iraqi society ... They deliberately did great harm to Iraq's ability to support itself as an industrial society ..."

"...Iraqis understood the legitimacy of a military action to drive their army from Kuwait, but they have had difficulty comprehending the Allied rationale for using air power to systematically destroy or cripple Iraqi infrastructure and industry: electric power stations (92 percent of installed capacity destroyed), refineries (80 percent of production capacity), petrochemical complexes, telecommunications centers (including 135 telephone networks), bridges (more than 100), roads, highways, railroads, hundreds of locomotives and boxcars full of goods, radio and television broadcasting stations, cement plants, and factories producing aluminum, textiles, electric cables, and medical supplies."

On 6 August 1990, after Iraq's invasion of Kuwait, the U.N. Security Council adopted Resolution 661 which imposed economic sanctions on Iraq, providing for a full trade embargo, excluding medical supplies, food and other items of humanitarian necessity, these to be determined by the Council's sanctions committee. From 1991 until 2003, the effects of government policy and sanctions regime led to hyperinflation, widespread poverty and malnutrition.

Highway of Death

If they think it was all justified, they are lost.