TEHRAN, Iran (AP) — Russian President Vladimir Putin’s visit to Iran starting Tuesday is intended to deepen ties with regional heavyweights as part of Moscow’s challenge to the United States and Europe amid its grinding campaign in Ukraine.

In only his second trip abroad since Russian tanks rolled into its neighbor in February, Putin is scheduled to hold talks with Iran’s President Ebrahim Raisi and Turkish President Recep Tayyip Erdogan about the pressing issues facing the region, including the conflict in Syria and a U.N.-backed proposal to resume exports of Ukrainian grain to ease the global food crisis.

As the West heaps sanctions on Russia and the costly campaign drags on, Putin is seeking to bolster ties with Tehran, a fellow target of severe U.S. sanctions and a potential military and trade partner. In recent weeks, Russian officials visited an airfield in central Iran at least twice to review Tehran’s weapons-capable drones for possible use in Ukraine, the White House has alleged.

But perhaps most crucially, Tehran offers Putin a chance for a high-stakes meeting with Erdogan, who has sought to help broker talks on a peaceful settlement of the Russia-Ukraine conflict, as well as help negotiations to unblock Ukrainian grain through the Black Sea.

Turkey, a NATO member, has found itself opposite Russia in bloody conflicts in Azerbaijan, Libya and Syria. But Turkey hasn’t imposed sanctions on the Kremlin, making it a sorely needed partner for Moscow.

Grappling with runaway inflation and a rapidly depreciating currency, Turkey also relies on the Russian market.

The gathering has symbolic meaning for Putin’s domestic audience as well, showing off Russia’s international clout even as it grows increasingly isolated and plunges deeper into confrontation with the West. It comes just days after U.S. President Joe Biden’s visited Israel and Saudi Arabia — Tehran’s primary rivals in the region.

From Jerusalem and Jeddah, Biden urged Israel and Arab countries to push back on Russian, Chinese and Iranian influence that has expanded with the perception of America’s retreat from the region.

It was a tough sell. Israel maintains good relations with Putin, a necessity given Russian presence in Syria, Israel’s northeastern neighbor and frequent target of its airstrikes. Saudi Arabia and the United Arab Emirates have so far declined to pump more oil beyond a plan approved by their energy alliance with Moscow.

But all the countries — despite their long-standing rivalries — could agree on drawing closer to counter Iran, which has rapidly advanced its nuclear program since former President Donald Trump abandoned Tehran’s atomic accord with world powers and reimposed crushing sanctions. Talks to restore the deal have hit a deadlock. On his trip, Biden said he’d be willing to use military force against Iran as a last resort.

Backed into a corner by the West and its regional rivals, the Iranian government is ramping up uranium enrichment, cracking down on dissent and grabbing headlines with optimistic, hard-line stances intended to keep the Iranian currency, the rial, from crashing. Without sanctions relief in sight, Iran’s tactical partnership with Russia has become one of survival, even as Moscow appears to be undercutting Tehran in the black market oil trade.

“Iran is (the) center of dynamic diplomacy,” Iranian Foreign Minister Hossein Amirabdollahian wrote on Twitter, adding the meetings will “develop economic cooperation, focus on security of the region via political solution … and ensure food security.”

Fadahossein Maleki, a member of the Iranian parliament’s influential committee on national security and foreign policy, described Russia as Iran’s “most strategic partner” on Monday. His comments belied decades of animosity stemming from Russia’s occupation of Iran during World War II — and its refusal to leave afterward.

Putin’s foreign affairs adviser Yuri Ushakov called Iran “an important partner for Russia” in a briefing Monday, saying the countries shared “a desire to take their relations to a new level of strategic partnership.”

In his fifth visit to Tehran, Putin will meet Iran’s Supreme Leader Ayatollah Ali Khamenei, with whom he has a “trusting dialogue,” Ushakov said. He will also hold talks with President Raisi on issues including Tehran’s nuclear deal, of which Russia is a key signatory. The leaders met in Moscow in January and again last month in Turkmenistan.

The focus of the talks among the three presidents will be the decade-old conflict in Syria, where Iran and Russia have backed President Bashar Assad’s government, while Turkey has supported armed opposition factions. Russia intervened in the conflict in 2015, pooling efforts with Lebanon’s Hezbollah militants and Iranian forces and using its air power to shore up Assad’s fledgling military and ultimately turning the tide in his favor.

Ushakov said the parties will discuss efforts to encourage a political settlement, while Erdogan is expected to take up Turkey’s threats of a new military offensive in northern Syria to drive away U.S.-backed Syrian Kurdish fighters from its borders. The operation is part of Turkey’s plans to create a safe zone along its border with Syria that would encourage the voluntary return of Syrian refugees.

Russia strongly opposes to the planned Turkish incursion, Ushakov stressed. Humanitarian issues in Syria have also come into focus since Russia used its veto power at the U.N. Security Council last week to force a restriction in aid deliveries to 4.1 million people in Syria’s rebel-held northwest after six months, instead of a year.

Talks to lift a Russian blockade and get Ukraine’s grain into global markets will also be on the agenda. Last week, U.N., Russian, Ukrainian and Turkish officials reached a tentative agreement on some aspects of a deal to ensure the export of 22 million tons of desperately needed grain and other agricultural products trapped in Ukraine’s Black Sea ports by the fighting.

Tuesday’s meeting between Putin and Erdogan could help clear the remaining hurdles, a major step toward alleviating a food crisis that has sent prices of vital commodities like wheat and barley soaring.