twelve reasons ww II wasn't a good war, with some introductory comments expanding on the subject;

The U.S. War Department was renamed the Defense Department in 1947, and it is common in many countries to speak of the war departments of one’s own and all other nations as “defense.” But if the term has any meaning, it cannot be stretched to cover offensive war making or aggressive militarism.  If “defense” is to mean something other than “offense,” then attacking another nation “so that they can’t attack us first” or “to send a message” or to “punish” a crime is not defensive and not necessary.

In 2001, the Taliban government in Afghanistan was willing to turn Osama bin Laden over to a third nation to be tried for crimes the United States was alleging he’d committed. Instead of pursuing legal prosecutions for crimes, the United States and NATO chose an illegal war that did far more damage than the crimes, continued after bin Laden was said to have left the nation, continued after bin Laden’s death was announced, and did serious lasting damage to Afghanistan, to Pakistan, to the United States and NATO nations, and to the rule of law.

According to a transcript of a meeting in February 2003 between U.S. President George W. Bush and the Prime Minister of Spain, Bush said that President Saddam Hussein had offered to leave Iraq, and to go into exile, if he could keep $1 billion. A dictator being allowed to flee with $1 billion is not an ideal outcome. But the offer was not revealed to the U.S. public. Instead, Bush’s government claimed a war was needed to defend the United States against weapons that did not exist. Rather than losing a billion dollars, the people of Iraq saw the loss of hundreds of thousands of lives, millions made refugees, their nation’s infrastructure and education and health systems destroyed, civil liberties lost, vast environmental destruction, and epidemics of disease and birth defects — all of which cost the United States $800 billion, not counting trillions of dollars in increased fuel costs, future interest payments, veterans’ care, and lost opportunities — not to mention the dead and injured, increased governmental secrecy, eroded civil liberties, damage to the earth and its atmosphere, and the moral damage of public acceptance of kidnapping, torture, and murder..........https://worldbeyondwar.org/necessary/