No 9/11. The West doesn't go into Afghanistan. Iran and Pakistan both intervene there in support of favoured factions (and , at least in Iran's case, historical claims to overlordship) and the situation escalates...
The 1998 Crisis between Iran and the Taliban could well have led to a war between Pakistan and Iran.
Make a war between Iran and Pakistan, similar to the Iraq-Iran war.
POD is 1945.