ANKARA — Turkey and the United States will aim to smooth out a series of disagreements between the NATO allies when the Turkish foreign minister visits Washington this week. But expectations that outstanding issues can be resolved are low.

Mevlut Cavusoglu departs on Tuesday for a meeting with U.S. counterpart Antony Blinken on a rare visit by a top Turkish official. U.S. President Joe Biden ‘s administration has kept its distance from Turkey because of President Recep Tayyip Erdogan ‘s increasingly authoritarian direction and policies curbing rights and freedoms.

Positioned at the crossroads between East and West, Turkey remains strategically important for Washington. Last year, the Turkish government helped broker a crucial agreement between Russia and Ukraine that allowed millions of tons of Ukrainian grain to be transported to world markets, averting a food crisis amid the war.

NATO allies, however, frequently find themselves at odds over a number of issues, with the biggest disputes centering on Turkey’s purchase of Russian-made missiles and American support for Kurdish militants in Syria.

The acquisition of the S-400 air defense system in 2017 led to sanctions and Turkey being removed from the development program for the next-generation F-35 fighter plane. After losing out on the F-35, Ankara is currently trying to restock its F-16 fleet. But the deal faces opposition in Congress.

Cavusoglu sounded confident this week that the deal for the purchase of 40 F-16 jets as well as technology for the update of its existing fleet would overcome congressional hurdles.

“We have reached an agreement with the (Biden) administration, and it is important that the administration has emphasized that the agreement is not only important for Turkey but for NATO as well,” Cavusoglu told reporters. “If the administration stands firm … then there will be no problem.”

U.S. State Department deputy spokesman Vedant Patel responded Friday to media reports that the Biden administration is also seeking congressional approval for shipping F-35s to Greece, another NATO member and neighbor that is growing increasingly irritated by Ankara’s threats.

“Türkiye and Greece both are vital, vital NATO allies and we have a history of, of course, supporting their security apparatuses. But I’m just not going to get ahead of the process here,” Patel said using the name for Turkey preferred by Erdogan’s government.

In Syria, U.S. support for the Kurdish militant group YPG since 2014 has angered Ankara because of links between the YPG and the Kurdistan Workers’ Party, or PKK, which has waged a 39-year insurgency against Turkey and is listed as a terrorist organization by the U.S. and European Union.

Backing for the YPG has led senior Turkish officials to accuse Washington of ties to terror attacks such as November’s Istanbul bombing that killed six people.

U.S. concern over Ankara’s cozy relationship with the Kremlin has been reinvigorated by the war in Ukraine. Despite Turkey’s ties with Moscow producing breakthroughs such as the grain deal and prisoner swaps, Washington is worried about sanctions-busting as Turkish-Russian trade levels have risen over the last year.

Ankara’s feet-dragging over ratifying bids by Sweden and Finland to join NATO has added to friction between the allies.

Turkey’s recent attempts at rapprochement with Syria after a decade of bitter enmity has opened another break with the U.S. Following a meeting of Syrian and Turkish defense ministers in Moscow last month, the U.S. State Department reiterated its opposition to countries normalizing relations with Damascus.

On Thursday, the department’s main spokesman, Ned Price, said at a regular media briefing that “we have not seen that this regime in Damascus has done anything that would merit normalization or merit improved relations.”

“Anyone engaging with the regime should ask how that engagement is benefiting the Syrian people – again, a people that have borne the vicious brunt of what their own government has inflicted upon them,” Price added.

The U.S. military has also warned that a threatened Turkish operation against the YPG in northern Syria could destabilize the region and revive the Islamic State group.

In another long-standing dispute, the U.S. Supreme Court was due to hear the Halkbank case on Tuesday. The Turkish state-owned lender is accused of money laundering, bank fraud and conspiracy for allegedly helping Iran evade sanctions. Lawyers for the bank say the 2019 indictment is unlawful under the Foreign Sovereign Immunities Act.