Qatar is looking for more investment opportunities in Russia to capitalize on “huge” growth potential and is fully satisfied with its purchase of around a fifth of Russian state oil producer Rosneft PJSC, the Gulf state’s ambassador in Moscow said.

“The company with its valuation has been attractive,” Fahd bin Mohammed Al-Attiyah said in an interview in the Russian capital. “It’s a great investment and we’re very happy to be part of it.”

The Qatar Investment Authority emerged as a major shareholder in Rosneft in May last year after a $9 billion deal to sell a stake to China’s troubled CEFC Energy Co. collapsed. The sovereign wealth fund now owns 18.93 percent of Rosneft, making it the third-largest shareholder after the Russian state, which holds 50 percent, and U.K. oil major BP Plc with 19.75 percent.

Rosneft’s share price has risen about 6 percent since QIA and commodity trader Glencore Plc agreed to buy a 10.2 billion euro ($11.5 billion) stake in December 2016. The deal cemented Doha’s links with Moscow at a time when Qatar is facing isolation from Saudi Arabia and other Gulf countries. Russian Foreign Minister Sergei Lavrov last week began a four-nation Gulf tour with Qatar, traveling on directly to Saudi Arabia despite a ban on air links between the two rival nations.

Qatar has invested heavily in Russia in recent years. QIA in 2013 bought a $500 million stake in Russian state-owned VTB bank and controls 25 percent in the operator of St. Petersburg’s Pulkovo airport as part of planned $2 billion of investments via a joint venture with the Russian Direct Investment Fund. State-owned Qatar Airways last year also agreed to buy a 25 percent stake in Moscow’s Vnukovo airport.

While the Qatari ambassador didn’t specify potential new areas of investment, RDIF has highlighted financial, retail, mining and infrastructure sectors as targets for Qatar.

“We see Russia’s economy to be stable and the potential for growth is huge,” Al-Attiyah said.

Even so, U.S. sanctions on Russia pose a risk that present an “obstacle” in negotiations for Qatar to purchase the S-400 missile-defense system, he said.