OPEC and its allies outside the group agreed to maintain oil production cuts until the end of 2018, extending their campaign to wrest back control of the global market from America’s shale industry, Bloomberg reported.

After a day of talks in Vienna, the decision showed the strength of the unprecedented alliance between the world’s top two oil producers, Saudi Arabia and Russia, and confounded Wall Street analysts who predicted Moscow would be reluctant to keep going. The deal was even beefed up through the inclusion of Nigeria and Libya, two members of the Organization of Petroleum Exporting Countries originally exempted from the curbs.

“We are united, shoulder to shoulder,” Saudi Arabian Energy Minister Khalid Al-Falih said sitting next to his Russian counterpart Alexander Novak at a press conference after the meeting. “We are completely aligned.”