The US Treasury Department added a field operated by Gazprom to its list of targeted economic sanctions, reported the Sofia News Agency.

The field, known as the Yuzhno-Kirinskoye oil and gas field in the Sea of Okhotsk, is resource-rich in both oil and natural gas, with reserves of approximately 640 bcm of the latter.

The US enacted the sanctions over sharp disagreements with Russia over the occupation of Ukraine’s Crimea region and continued fighting in the country’s west.

The most recent action is believed to be the first time the US has applied sanctions against an oil field, rather than a corporation of individual. Ukraine Today stated that a number of European measures have been put forward with similar effects to the US decision.