BRUSSELS (AP) — European Union foreign ministers will gather Sunday to discuss the impact of Donald Trump’s election on trans-Atlantic ties and whether it will complicate relations with an increasingly belligerent Russia.

At informal dinner talks in Brussels, well away from the media, the ministers will debate how many of Trump’s campaign announcements — like isolationist positions on security, his rejection of international trade pacts and refusal to criticize Russian President Vladimir Putin — might translate into real policy.

Before the dinner, EU diplomats were at a loss to explain Trump’s stunning victory or understand yet what it might really mean.

Giovanni Grevi, senior fellow at the European Policy Centre think tank, said that “cooperation between Europe and the U.S. will not become impossible, but it will become much more difficult.”

“Donald Trump has been putting America first … in defining his foreign policy and it seems he is taking a very transactional approach to international affairs. This is very likely to apply also to trans-Atlantic relations. He will value Europeans in so far as they can match his priorities,” Grevi said.

Given Trump’s clear opposition to major trade pacts, EU officials are all but certain that the massive Trans-Atlantic Trade and Investment Partnership, or TTIP, will have to be renegotiated, if any life remains in the project at all.

“With the new president-elect we don’t really know what will happen. There is strong reason to believe that there would be a pause in TTIP, that this might not be the biggest priority for the new administration,” EU Trade Commissioner Cecilia Malmström said Friday.

Perhaps the most pressing problem though is to understand how Trump wants to deal with Putin.

The EU has imposed sanctions on Russia over its annexation of Crimea and destabilizing role elsewhere in Ukraine. Some of those measures, including asset freezes on individuals and organizations, come up for renewal in January.

EU leaders are due to discuss them at a summit in Brussels on Dec. 15-16, but any signal from Trump about a softening of U.S. relations with Russia is likely to embolden already-reluctant countries like Germany, Italy and others to push for an end the sanctions regime, diplomats said.

The EU foreign ministers will meet again formally on Monday, to discuss strained ties with membership candidate country Turkey, the conflict in Syria and Libya, and defense cooperation with the NATO military alliance.