Saudi Arabia’s King Salman arrived in Moscow on Wednesday in the first-ever official visit by a Saudi monarch to Russia, in a mission that signals an expanding Russian role in the geopolitical landscape of the Middle East as the Syrian civil war approaches an endgame.

The king’s visit to Moscow would have been unthinkable just two years ago, when Russia intervened in the Syrian conflict on the side of President Bashar Assad. Russian airpower helped turn the tide of the war, supporting Assad’s troops as they moved to crush an armed insurrection that raged since 2011. Saudi Arabia and other Gulf states sided with the opposition, and those governments are now grappling with the reality that Assad will not be ousted.

For Russia, King Salman’s trip illustrates its growing footprint in the politics of the Middle East after its military rescued the Assad regime from the threat of collapse. Under President Vladimir Putin, Russia has become a key broker in the political struggle in Libya, and is improving ties with predominantly Sunni Arab Gulf states who seek Russia’s help in curbing the influence of Iran—an ally of Moscow and an archrival of Saudi Arabia. Putin has shown a striking ability to transcend traditional dividing lines in the region, also cultivating ties with Israel, Palestinian factions, and Egypt.

“For the Russians it’s definitely continuing to project the image of a great power in the Middle East,” says Yury Barmin, an expert on Russian relations in the Middle East, speaking from Moscow. “They’re looking to create new contexts, to create new partnerships where they could be seen as an influential actor,” he added.

The emerging partnership between Russia and Saudi Arabia is fueled by a shared economic lifeblood: oil. The two states are now leading an initiative to cut world oil production in order to drive prices up, reversing a catastrophic slide in the price of crude that resulted from the North American shale oil boom. Russia is now the largest country outside of the oil producers’ cartel OPEC that is complying with the plan to curb production. The two countries produce nearly a quarter of the world’s oil between them, and crude is a critical source of revenue for both states.

Saudi Arabia is expected to expand its oil ties with Russia during King Salman’s visit. Saudi Aramco, the giant state oil company, is expected to sign a series of agreements with Russian companies on energy initiatives. Saudi Arabia is also considering investing largest oil drilling contractor, Eurasia Drilling Co, according to Bloomberg. The final shape and scale of any investment has yet to be announced, and past Saudi-Russian economic cooperation has failed to materialize.

The visit suggests the Saudi government is pursuing a more balanced approach to the U.S.-Russian rivalry, a move that poses strategic questions for Washington. Saudi Arabia is one of the United States’ closest allies in the Arab world, and it has traditionally been aligned against Russia, dating back to Saudi Arabia’s support for anti-Soviet mujahideen in Afghanistan in the 1980s. Along with other Gulf states, the Saudis embraced the election of President Donald Trump, who they hoped would end years of friction with President Barack Obama, whose initial embrace of the Arab Spring uprisings, mild prodding on human rights, and nuclear diplomacy with Iran alienated the autocratic regimes along the Persian Gulf.

Yet, despite feteing Trump during the president’s first foreign voyage in May, the Saudi government’s enthusiasm has faded as the Trump administration has struggled to find ways to check the expansion of Iran’s influence on the ground in the region. Pro-Iranian militias are playing a key in the battle to degrade the Islamic State in Iraq. Iran also sent its forces to aid the Assad regime in Syria. In June Saudi Arabia led a quartet of countries imposing sanctions on neighboring Qatar, demanding that the tiny nation end its unusually warm ties with Iran, but the dispute settled into a standoff.

“It’s not necessarily an indication that they’re moving away from the United States, but I think they’re hedging their bets a little bit on the U.S.,” says Gerald Feierstein, the former U.S. ambassador to Yemen and the current director of Gulf affairs at the Middle East Institute in Washington. “They want to make sure that they’ve got a number of different addresses that they can visit to pursue their own interests,” he said.

The shifting Saudi Arabia-Russia relationship is also a stark illustration of how regional powers are dealing with a new phase of the conflict in Syria. With Russian and Iranian backing, the Assad regime has ensured its own survival inside a rump state within Syria. The armed rebellion against Assad is now confined to isolated enclaves in Syria’s northwest, southwest, and the outskirts of Damascus. The United States and the United Kingdom also recently ended clandestine programs that had provided aid to the rebels. Analysts say that Russia’s ability to outflank western powers in Syria is reshaping the face of the region.

“Russia’s resilience in the face of such efforts has been strengthened by the lack of serious Western action to push for political change in Syria. These dynamics have come to define a new balance of power in the Middle East,” says Lina Khatib, the head of the Middle East and North Africa Program at Chatham House in London. “Arab states are now faced with the challenge of maintaining their relevance in the face of this change, and this means needing to keep lines of communication with Russia open.”

One mystery about the King’s visit was why the kingdom’s other high-profile leader, his 32-year-old son and newly appointed Crown Prince Mohammed Bin Salman, did not join him on the trip. He had been expected to attend the high-stakes diplomatic mission, which offered an opportunity to demonstrate his legitimacy as a future head of state.

A bulletin on Saudi Arabia’s official news agency gave no explanation why the crown prince did not travel with the king, saying only that he had tasked Mohammed Bin Salman with managing the state’s affairs in his absence.

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