UNCLOS imposes no new restrictions on interdiction over what was agreed to in 1958 convention

The most absurd argument made against the Convention is the notion that it would hinder U.S. efforts to interdict shipments of materials used for nuclear, chemical and biological weapons and the missiles used to deliver them. The opposite is true. Signing the Convention helps stop proliferation.

Opponents contend that because the Convention protects freedom of the seas and freedom of already passage in territorial waters, signing would prohibit the U.S. Navy from stopping suspect shipments.¹² This argument is based on a misunderstanding of both international law and America’s current nonproliferation efforts. The Convention offers states limited reasons for violating a ship’s freedom of the seas or right of innocent passage, and these reasons do not include carrying weapons. But these constraints on U.S. conduct already exist. Freedom of the seas and the right of innocent passage are codified in the treaties the United States passed in 1958 and subsequently recognized as customary international law. If the United States ever had a right to stop shipments without regard for freedom or the seas and the right of innocent passage, that right is long gone. The Convention imposes no new restrictions on the United States’ ability to interdict weapons shipments.