The European Union's top two officials will pay a rare visit on Tuesday to Turkish President Recep Tayyip Erdogan aimed at testing his avowed commitment to improve uneasy ties.
Years of disagreements over a growing list of issues threatened to boil over last summer when Turkey sent navy ships to support an energy exploration mission in waters claimed by EU members Cyprus and Greece.
Tensions cooled somewhat when Turkey withdrew the vessels and this year engaged in its first maritime talks with Greece since 2016.
The bloc pulled back from its threat to sanction Turkey as a result.
European Commission chief Ursula von der Leyen and European Council president Charles Michel will now see how Erdogan intends to follow through on his repeatedly stated desire to "turn a new page" in relations.
- Setting of terms -
The Turks say they want to move forward from "positive" talks held in a series of calls to "concrete action" -- especially on migration.
But EU officials warn that any improvement depends on how Erdogan -- who was leader when Turkey formally opened talks to join the bloc in 2005 -- acts and whether he remains a constructive partner.
The possible thaw coincides with a toughening on Turkey from the White House, where the election of President Joe Biden saw Erdogan lose a personal friend in Donald Trump.
In a "carrot-and-stick" approach, the EU is dangling the possibility of updating the sides' customs union, visa liberalisation, providing more money for refugees and increased dialogue with Turkey on several fronts.
But an EU official insisted that Tuesday's meeting "will not be a moment of negotiations" but rather a chance for the sides to lay out their terms for improved ties.
- List of grievances -
The meeting comes on the heels of Turkey's withdrawal last month from a treaty combating violence against women and the launch of a formal bid to shut down the country's main pro-Kurdish party.
Although Brussels condemned both decisions, EU leaders last month still reiterated their commitment to work with Turkey if the "current de-escalation is sustained".
Both sides have lists of grievances they want addressed.
A Turkish diplomatic source told AFP that Ankara expects the modernisation of 1995 Customs Union and greater emphasis on Turkey's candidacy status to join the EU.
The source added Turkey wanted to update their 2016 migration agreement, which saw the bloc promise billions of euros in exchange for Turkey exerting control over the flow of migrants and refugees into Europe.
Turkey is home to nearly four million refugees and migrants, the majority of whom are Syrian.
"The EU hasn't yet fully lived up to its commitments to the deal, in particular its financial liabilities," the source said, adding only 3.7 billion euros ($4.4 billion) of the promised six billion euros had reached Turkey.
Brussels accuses Ankara of not following through on its commitment to take back migrants who make it to Europe but whose asylum applications fail.
- Thorn of Cyprus -
Ilke Toygur, an analyst at the German Institute for International and Security Affairs, said Turkey wanted a transactional relationship with the bloc, "keeping its options open".
The Turkish government sees a "more multi-polar, more divided" world with the declining influence of the West, Toygur told a podcast for her think tank, adding: "Turkey sees this as an opportunity to also diversify its allies."
Turkey's increasingly assertive foreign policy has been a significant source of EU-Turkey strains.
These escalated over Turkish support to Azerbaijan during a war in Nagorno-Karabakh last year against Armenia and Ankara's military backing to Libya.
But with ceasefires agreed in those conflicts, the sides are now focusing on UN-led exploratory talks over the divided island of Cyprus scheduled for later this month.
Cyprus has been a thorn in relations since 1974, when Turkey occupied the island's northern third in response to a coup orchestrated by the military junta then in power in Athens aimed at annexing the island to Greece.