Senior U.S. and Turkish officials are set to meet at the State Department for several rounds of talks focusing on topics spanning Syria, Russia's invasion of Ukraine, defense cooperation, energy, counterterrorism and the Israel-Hamas war.

The conversations, dubbed the Strategic Mechanism, will set the stage for a meeting on Friday between U.S. Secretary of State Antony Blinken and Turkish Foreign Minister Hakan Fidan.

Ties between the U.S. and Turkey have drifted away from a strategic partnership in recent years as disagreements between the two long-standing treaty allies have widened.

Turkey's 2019 acquisition of Russian S-400 defense missile system triggered U.S. sanctions on Ankara and led to its removal from the F-35 stealth fighter jet program. Meanwhile, Turkey has remained deeply troubled over U.S. support in northern Syria to Kurdish militia that it sees as an extension of the PKK, a militant group it considers as a terrorist organization.

The U.S. was also annoyed by Ankara's 20 month-long delay in approving Sweden's NATO membership, which took place in January. The U.S. Congress has since approved the $20 billion sale of F-16 fighter jets to Turkey, long sought by the Turkish government.

Since then, U.S. officials have begun describing a desire on both sides to deepen conversations in areas where the two sides can cooperate.

"This is probably going to be the meatiest and most positive strategic mechanism that we’ve had in years," a senior U.S. official said of the upcoming conversations.

In late January, U.S. Senators from President Joe Biden's Democratic Party Jeanne Shaheen and Chris Murphy visited Turkey and met with Erdogan. Murphy then said there was now "significant momentum" in the bilateral ties.

In an interview with Reuters, Shaheen described their visit as "quite positive in terms of the potential to reset U.S.-Turkey relations going forward."

TOUGH CONVERSATIONS

However, there is no illusion the two-day visit will solve all long-running strains between the two allies and some tough conversations are expected.

The hardest talks will likely take place on the way forward in Syria and Ankara's strong economic ties with Russia, which Washington says has helped the Kremlin circumvent some U.S. sanctions on Moscow.

Shaheen said she discussed with Erdogan Ankara's relationship with Moscow, arguing it is not in Turkey's interest to have Russian President Vladimir Putin "feel like he can take over whatever country he would like", an apparent reference to its invasion of Ukraine.

"The potential is much greater for the United States and Turkey to work together than for Turkey and Russia to work together," Shaheen said.

Ankara opposes Western sanctions on Moscow even as it has criticised Russia's invasion of Ukraine. It has managed to maintain close ties with both Moscow and Kyiv throughout the conflict.

It held early talks between the sides and helped broker a deal for grain shipments from Ukraine.

In the meantime, its trade with Moscow boomed before a U.S. executive order in December complicated some Turkish payments for Russian oil as well as Russian payments for a broad range of Turkish exports.

Senior U.S. officials repeatedly traveled to Turkey to warn Turkish companies against the risk of running afoul with U.S. sanctions.

"I think we're seeing a lot better cooperation there," U.S. Ambassador to Turkey Jeff Flake said in the same interview.

On Syria, any breakthrough will likely remain elusive after years of disagreements.

Washington's Syria policy is focused on fighting against Islamic State remnants and training partnered forces.

Spearheaded by the Kurdish People's Protection Units (YPG) and including Arab fighters, the Syrian Democratic Forces militia has been a major partner for the U.S.-led coalition against Islamic State over the last decade.

Turkey wants the U.S. to stop its support for the Kurdish militia.

"Obviously we see things different in some respects but...our interests align when it comes to defeating ISIS," Flake said. "We're trying to build on the areas that we have a collective interest despite some differences we have there."