Maine’s independent senator has proposed that the U.S. military play a role in reducing carbon emissions by converting some vehicles to electricity.U.S. Sen. Angus King’s bill calls for transitioning the non-tactical fleet of the U.S. Department of Defense to electric and other zero-emission vehicle types. King said his proposal would require three quarters of non-tactical vehicles purchased by the department to be electric or zero-emission and made in the U.S. Non-tactical vehicles include cars, vans and some trucks.