The Oath of Office: Duty to the Constitution

The modern Oath of Office

§3331. Oath of office
An individual, except the President, elected or appointed to an office of honor or profit in the civil service or uniformed services, shall take the following oath: "I, AB, do solemnly swear (or affirm) that I will support and defend the Constitution of the United States against all enemies, foreign and domestic; that I will bear true faith and allegiance to the same; that I take this obligation freely, without any mental reservation or purpose of evasion; and that I will well and faithfully discharge the duties of the office on which I am about to enter. So help me God." . . .

The duty of an officer in the uniformed services "to support and defend" is not to any particular person nor to a group of people nor to a state nor to any service. The Oath is to the foundational document of the United States - its Constitution.

Interesting look at the history of this Oath here:

Oath of Office Historical G... by lawofsea on Scribd