At war includes:

• US troops on the ground in Iran

• Ongoing strikes by either side

• Strait of Hormuz closed to most traffic, and US Naval forces in the area

• Routine US overflights or Iran, such as an enforced no-fly zone

This is based on the status at the time Trump leaves office, not before; if the war pauses and then resumes and is ongoing when Trump leaves, this will resolve Yes, pause notwithstanding.

Resolution will be based on a consensus of credible reporting, relevant Wikipedia articles, and official government statements.