The Commander in Chief may at any time, in order to execute the law, suppress riots or insurrections, or to repel invasion, or for the purpose of aid and relief of citizens in disaster, in addition to the active National Guard, the inactive National Guard, and the Naval Militia, order out the whole or any part of the unorganized militia. When the armed forces of the state, or a part thereof, are called to duty under the Constitution and laws of the United States or the Constitution and laws of this state, the Governor shall first order out for service the National Guard or Naval Militia, or such part thereof as may be necessary, and, if the number available be insufficient, he may then order out such part of the unorganized militia, as he may deem necessary.