Schlumberger Ltd. (NYSE: SLB), the world’s largest oilfield services company, has agreed to buy a 51% stake in Russia’s biggest oilfield services firm Eurasia Drilling Co. (EDC), the Russian company said late on July 20.

It is Schlumberger’s second attempt to buy part of EDC and would be the first U.S. purchase of a stake in Russia’s oil and gas sector since sanctions were imposed on Moscow for its role in the Ukraine crisis and the annexation of Crimea in 2014.

“I warmly welcome Schlumberger as our majority shareholder. It builds on our strategic alliance with Schlumberger since 2011 and our mutually beneficial business relationship since 2007,” EDC CEO Alexander Djaparidze said in a statement.

In 2015, Schlumberger agreed to buy 45.65% of EDC for $1.7 billion, but the deal fell through after Russia’s antitrust regulator, the Federal Antimonopoly Service, repeatedly postponed its approval.

EDC then delisted its shares on the London Stock Exchange.

The new agreement is also subject to approval by the same antitrust body. Financial terms of the deal were not disclosed.

Xenon Capital acted as financial advisor to EDC, a source close to the deal told Reuters.

In June, the state-backed Russian Direct Investment Fund said a consortium of Russian, Chinese and UAE funds was buying a minority stake in Eurasia Drilling.

“Work on this investment remains ongoing and the company expects to enter into a definitive agreement in relation to it in the near future,” EDC said in the statement.