Is there an option to suspend auto insurance coverage when you are not in the United States?

Yes you can but you will need to speak directly to your insurance agent. Just explain your situation and they should be willing and able to accommodate your situation. If they give you a hard time about doing it, tell them that you want to put your vehicle(s) in storage. Insurance companies offer this type of insurance and it is really affordable. Just remember to notify them when you return so you will have your liability coverage returned to you upon driving.