Exactly sunshine. So Monroe's Doctrine and every bastardization since has no legal standing either. Because it wasn't in the document. And what does the document say about powers not explicit in the document? Where do those belong? Hmmmmm... and we all know what happened to that amendment
Article 1, Section 10 makes it pretty clear that the states are NOT permitted to exercise any foriegn policy of their own:
No state shall enter into any treaty, alliance, or confederation
No state shall, without the consent of Congress, lay any duty of tonnage, keep troops, or ships of war in time of peace, enter into any agreement or compact with another state, or with a foreign power, or engage in war, unless actually invaded, or in such imminent danger as will not admit of delay.
Article 2, Section 2, however, clearly points to giving the Executive the power to handle foreign policy:
He shall have power, by and with the advice and consent of the Senate, to make treaties, provided two thirds of the Senators present concur; and he shall nominate, and by and with the advice and consent of the Senate, shall appoint ambassadors, other public ministers and consuls....
Or, how about these from Article 1, section 8?
To regulate commerce with foreign nations, and among the several states, and with the Indian tribes;
To define and punish piracies and felonies committed on the high seas, and offenses against the law of nations; To declare war, grant letters of marque and reprisal, and make rules concerning captures on land and water;
To raise and support armies, but no appropriation of money to that use shall be for a longer term than two years;
All of these powers involve the conduct of foreign policy and the maintenance of our ability to do so. Exactly what course is charted is for the President and Congress to work out, through the normal checks and balances.