Along its history, the USA has used true o false "casus belli" (an excuse for begin the war) without thinking much if US citizens would be damaged or killed.
We can remember the Maine case, which was the excuse to attack the Spanish army in Cuba arround 1880. Now we know if the "accident" was an accident or an explosion caused for the americans against his own ship.
We can remember the Ship with famous people sent to Europe during the World War I, agains the advertisment of Germany with his submarine war.
We can remember the attack against Pearl Harbour. US government said that it was an unexpected attack, but in fact they knew about the plans of attack a few months ago. However, the US goverment wanted the war and they needed a casus belli because American people did not wish the war.
The casus belli for attacking Iraq was the chemical weapons, the terrorism, and another excuses, but how we can see there are not chemical weapons in Iraq.
Another casus belli for attack Iraq were the attaks of the towers and the Pentagon. Bush allegedly knew about the plans to attack the towers, but he needed an excuse to attack the Middle East, and the towers became the excuse.
When the USA wants to attack some country, they look for an excuse, is they don't have it, they make it, we in Latin America are familiar with this kind of excuses very well, we have suffered from them during the past dictatorship regimes.