The seizure of a number of ships in recent months tells an uncomfortable story. In today's multi-polar world, countries can grab other nations' vessels and get away with it.

It's not just Iran's detention of the U.K.-flagged Stena Impero in retaliation for the seizure of one its own tankers by Britain. In recent months, other incidents have occurred that had nothing to do with smuggling or fishing disputes, the standard reasons for vessels to be stopped and held by governments. These detentions are geopolitical in nature.

In November, Russia grabbed three small Ukrainian naval vessels that tried to break through its de facto blockade of the Kerch Strait, a barrier intended to defend an expensive bridge Moscow has built to annexed Crimea. It continues to hold the Berdyansk, Nikopol and Yeni Kapu and their crews — despite an order from the International Tribunal for the Law of the Sea to release them. Moscow disputes the tribunal's jurisdiction and maintains that the vessels crossed the border illegally.