I believe these are in conflict with the congressional power in the Constitution to call out the militia and the presidential power to command that militia. The militia, by law, is the armed citizenry. (An important issue in the gun debate.)
It might require an amendment removing the congressional and the presidential powers regarding the militia. (relevant also in the section on the draft.) Removing these from the Constitution would probably be a bad idea since they are provisions for extreme national emergency.
Art 1 (legislative), Sec 1: To provide for calling forth the Militia to execute the Laws of the Union, suppress Insurrections and repel Invasions;
Art 2 (executive), Sec 2: The President shall be Commander in Chief of the Army and Navy of the United States, and of the Militia of the several States, when called into the actual Service of the United States;
The Militia is, by definition, the voluntarily armed citizenry.
The Quakers have abdicated their Fatherly responsibility before God in their refusal to take up Arms in defense of their Families, but I tend to feel that they should have to answer to God for that, not the Government. The Government should not enjoy the Power to contravene the Quakers' "religious freedom" to behave like godless pacifists.
Rather, the Militia is itself a Voluntary institution, composed only of those who Volunteer to undertake their Godly Responsibilities to defend home and hearth -- and it is this "militia" which Congress constitutionally enjoys the Power to call up in time of War.
Of course, this would make it very difficult to wage Offensive Foreign Wars, as perhaps 90% of the USA's potential Military manpower might well refuse to Volunteer to "defend" Kosovo Albanian Islamofascists. By contrast, Defensive Domestic Wars would likely enjoy a 90% Volunteer ratio -- 9 out of 10 Citizens might not volunteer to defend Albania, but only perhaps 1 out of 10 Citizens would not volunteer to defend against a direct assault on their own Homeland.