Russia has sent naval vessels to escort an oil tanker being pursued by US forces across the Atlantic, according to reports from CBS News.
The tanker, now named Marinera, is not carrying cargo but has previously transported Venezuelan crude oil.
US President Donald Trump last month ordered a blockade of sanctioned vessels entering or leaving Venezuela.
The tanker was earlier targeted by the US Coast Guard in the Caribbean over alleged sanctions breaches and Iranian oil shipments.
After evading boarding, the vessel reportedly changed course, name and flag, re-registering as a Russian ship.
US officials said Washington prefers to seize the tanker rather than sink it if an operation proceeds.
The US military said it remains ready to act against sanctioned vessels transiting the region.
Russia said it is monitoring the situation with concern as the ship sails in international waters.
For reasons unclear to us, the Russian ship is being given increased and clearly disproportionate attention.
Russia’s foreign ministry said.
Maritime analysts said changing a ship’s name or flag does not alter its sanctions exposure.
The tanker was believed to be between Scotland and Iceland, with weather conditions complicating any boarding attempt.
The standoff follows the recent US operation in Caracas that led to the arrest of Venezuela’s former leader Nicolás Maduro.