The trigger for the invasion of Iraq in 2003 was nominally the necessity of taking out Saddam’s weapons of mass destruction. It turns out much of the information involved in the decision was FUD. An Iraqi has admitted fabricating information about chemical and biological weapons. Other information about nuclear weapons was similarly weak. 100K people have died for nothing on that account although displacing Saddam had some merit. Still that could have been accomplished with a few raids. There was no need for an invasion in force which resulted in destabilization of the whole country. Iraqis were not an enemy yet they have paid the price and continue to do so.
Sometimes war is necessary but there must be a clear and present danger, not fear, to justify the certain killing of humans in bulk, mostly harmless civilians. The risk of failing to prevent attack by WMD does not justify the certainty of major destruction. 100K dead as collateral damage is just as big a crime as 100K dead by WMD. Nations must follow reasonable standards of behaviour or humanity will descend back to the Stone Age where we survived rather than thrived.
My background is in physics which science formed the basics of nuclear war. Physicists have been blamed for unleashing that horror on humanity but in the particular war the atomic bomb clearly did and was intended to minimize casualties, including civilians by ending the war months or years sooner. The current fear of terrorism and WMD in the hands of terrorists and rogue states is blown far out of proportion in comparison to WWII. The idea that USA, UK, Israel, France, China, India, Pakistan, Korea and Russia are somehow OK to have nuclear weapons but no one else is ludicrous. Ask the dead Iraqis if they think it is great that the USA and others can invade and kill at will. Other countries that cannot afford nukes will find a way or resort to other forms of weapons either as a means of attack or retaliation. The problem is weapons and warlike attitudes, not technology. Even if Iran were to make nukes, that is not justification to start another war. We have had enough wars accomplish nothing.
We have often discussed return on investment here with respect to information technology but the terrorists were given huge return on the investment of a $million or so: $billions spent on security, $billions in damages, and many $billions on the wars in Iraq and Afghanistan. The disproportionate response to terrorism fuels it and gives it a much larger return than it should have. Quick strikes in Afghanistan and Iraq would have accomplished much more for the invested money and blood than protracted war if they were even necessary. Occupying territory just breeds resistance. Ask the Germans who tied up multiple armies holding territory against irregular forces all over Europe. Does no one learn from history?
Next time you hear that leaders require war because of threat X, remember the WMD and Iraq.