Airlines have canceled thousands of flights since the U.S. and Israel launched attacks on Iran over the weekend, disrupting plans for many travelers transiting through some of the world's busiest airports.

But many people who bought travel insurance as a financial backstop to protect against such travel disruptions may be out of luck.

That's because standard travel policies exclude coverage for disruptions tied to acts of war and military action, travel experts said.

The upshot: Vacationers who miss some or all of their trip might not be reimbursed by their insurer for various nonrefundable costs like flights, hotels or tours. Those stranded abroad may not be compensated for out-of-pocket costs incurred for extra meals or hotel nights.

"There are many situations where travel insurance will not cover you," said Sally French, a travel expert at NerdWallet.