http://personalinsure.about.com/od/personalproperty/a/Property-Insurance-Policy-Coverage-Exclusions.htm
Note the section titled "Extrtemely Hazardous Events.
I would classify riots and insurrection as being different than vandalism. The distinction may lie in how the local governments classify the events i.e. disaster areas or martial law decrees.
It would be a good idea to familiarize yourself with any policies in the regard. You can bet that any gray areas would benefit the insurance companies.
Interesting. Thank you for the information.