U.S. sanctions on Russia and Venezuela have boosted tonne-miles, increased floating storage, and shifted trade from shadow fleets to mainstream tankers.

The first sanctioned oil tanker was seized on Dec. 10 as part of an effort to push former Venezuelan President Nicolas Maduro from power.

The U.S. has returned a Panama-flagged supertanker, M/T Sophia, to Venezuela after seizing it as part of broader measures targeting Venezuelan oil tankers. The Sophia is part of a 'dark fleet' and had been carrying oil when interdicted.

The U.S. seized two tankers linked to Venezuelan oil exports, most notably a Russian-flagged oil tanker that was being shadowed by a Russian submarine. American forces had been pursuing the Marinera for more than two weeks across the Atlantic. The U.S. Coast Guard also intercepted the M Sophia in the Caribbean.

Faris Tanyos is a news editor for CBSNews.com, where he writes and edits stories and tracks breaking news. He previously worked as a digital news producer at several local news stations up and down the West Coast. The United States on Tuesday morning ...

China route have surged to their highest level since November as tight vessel supply and lingering U.S.-Iran tensions keep freight markets under pressure.