The Additional Protocol was adopted on the initiative of the United States. The Convention of 1907 seemed to be in conflict with the Constitution of the United States which vests the judicial power in the Supreme Court. The delegates assembled at the Naval Conference in London in 1908 and 1909 approved in principle the modifications submitted to them by the United States, but were not authorized to sign an additional protocol. The Additional Protocol was signed at The Hague by thirteen Powers and was later signed by all the remaining signatories of the original Convention.