BERLIN (AP) — European Union foreign ministers plan to tackle one of the bloc's most urgent and complex challenges Thursday as they try to persuade member nation Greece and its neighbor Turkey to pull back from the brink of conflict in the Mediterranean Sea.

At informal talks in Berlin, the ministers are set to debate a range of sanctions and other policy options that might convince Turkey - still a candidate for membership in the 27-nation EU - to temper its insistence on drilling for energy reserves in disputed parts of the eastern Mediterranean.

The two-day meeting comes as Turkey and Greece, which are both members of the NATO military alliance, rattle sabers with warships and war games in the area, and as their leaders swap barbs over which of them is in the right and how far they would be willing to go to defend their interests.

Turkish President Recep Tayyip Erdogan vowed Wednesday that his country “will never compromise on what belongs to us. We are determined to do whatever is necessary in political, economic and military terms.”

Germany, which currently holds the EU’s rotating presidency, has been trying to mediate between Athens and Ankara. Foreign Minister Heiko Maas visited both capitals on Tuesday, warning that “any spark, however small, could lead to a disaster.” Apparently, he had little success.

Asked Wednesday by EU foreign policy chief Josep Borrell how well the meetings went, German Defense Minister Annegret Kramp-Karrenbauer, apparently unaware that a microphone was picking up her remarks, replied, “Hard. A little bit more smooth on the Greek side, but very hard on the Turkish side.”

Borrell responded that “the Turkish are very upset” and that “they feel that the Greeks are not reliable.”

The EU insists that “all options are on the table” during the foreign ministers' meeting, which Borrell will chair. That includes sanctions aimed at changing Turkey’s course of action, but also other political and diplomatic sticks and carrots. One country has suggested withdrawing Turkey’s EU candidate status.

Briefing reporters ahead of the talks, a senior EU official said that “in the mind of Borrell, what we have is a serious risk to escalate militarily in the eastern Mediterranean. His main concern is to try to reverse that situation.”

The official, who is not permitted to be named publicly, said that Borrell is not thinking about “huge and sophisticated foreign policy designs to attract Turkey to our position, but basically stopping what could have very serious, unintended, not desirable consequences.”

“All the options are on the table, because we are living really very challenging times in the relationship with Turkey. We have not seen that before,” the official said.

It’s unclear what might stop behavior that the EU considers illegal and Turkey sees it as defending its clear rights. Steps were taken in the past, inclduing the slashing of funds meant to prepare Turkey for EU membership and the virtual freezing of its accession talks, yet Ankara has only become more vocal.

On top of that, Turkey's president has shown his willingness to encourage migrants and refugees from Syria to cross the border into Greece to ensure the EU understands his demands. Europe remains deeply destabilized by the arrival in 20015 of well over 1 million asylum-seekers.

Turkey also plays a military role in Libya, a main jumping off point for migrants hoping to reach Europe.

Despite the urgency, no clear decisions about how to handle the EU’s increasingly troublesome neighbor are expected in Berlin. The ministers’ main task will be to agree politically on a series of options for national leaders to choose from at their next summit on Sept. 24-25.

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Cook reported from Brussels.