Russia Rejects Jurisdiction of Int'l Tribunal for Law of the Sea

The Netherlands has commenced proceedings before the International Tribunal for the Law of the Sea, for an order that Russia release the Dutch activists that Russia has detained for interfering with Russian energy exploration activity in the Arctic. Russia, however, has refused to recognize the jurisdiction of the tribunal, notwithstanding that it is a party to the UN Convention on the Law of the Sea. What legitimate grounds, if any, would it have for doing so?