When it comes to wars, the U.S. hardly learns from its mistakes. It invaded Afghanistan in 2001, vowing to destroy al-Qaeda. defeat the Taliban and “democratise” the country. But 20 years later, it handed it back to the Taliban. It invaded (and destroyed) Iraq in 2003, lying that Baghdad possessed weapons of mass destruction. It invaded (and destabilised) Libya in 2011 in the name of protecting Libyans from their government. In the case of Iran, America’s intelligence agencies concluded in March that Iran did not have an active weaponisation programme. Iran once signed a nuclear agreement with the U.S. and other major powers and accepted checks on its nuclear programme. It was Mr. Trump who tore up the deal. Iran again joined talks with the U.S., and it was Benjamin Netanyahu, Israel’s Prime Minister, who destroyed diplomacy this time. This war will have serious consequences for West Asian stability and global order. Major powers will now have less incentive to trust Mr. Trump’s overtures for dialogue. Smaller powers will have greater incentive to join the arms race for their own survival. North Korea will never give up its nukes. If Iran’s regime survives this storm, it could seek to rebuild its nuclear programme. If it decides to strike American bases, the war could spiral into something more dangerous. Mr. Netanyahu’s unchecked militarism, which is in part aimed at protecting his hold on power at home, has plunged the region into a deep security abyss. Mr. Trump has made it catastrophically worse by turning Israel’s war into America’s war. Darker days lie ahead for West Asia.