EU officials said Friday that one or more European leaders would need to grant Vladimir Putin a special waiver to fly through their airspace if he is to attend a proposed Budapest summit with Donald Trump.

The U.S. president announced this week that he would be holding direct talks with the Russian leader to try to end what he called an “inglorious” full-scale invasion of Ukraine that has dragged on for more than three years.

The meeting would be hosted in Budapest, where Prime Minister Viktor Orbán has cultivated friendly ties with both leaders.

But due to a ban on Russian aircraft flying through EU airspace linked to a wider sanctions regime, the Russian president would not be able to reach Budapest without defying the EU measures, taking a huge risk by flying over Ukraine, or going via a circuitous Balkan route.

Under the EU’s sanctions regime, national authorities may consider exceptions to the ban for Russian travel “if the competent authorities have determined that such landing, take-off or overflight is required for humanitarian purposes or for any other purpose consistent with the objectives of this regulation,” according to the EU legal text on the sanctions.

European Commission spokesperson Anitta Hipper confirmed during a briefing with journalists that individual EU countries could make exceptions to the travel ban.

Neither Putin nor his foreign minister, Sergey Lavrov, are currently subject to individual bans on travel within the EU, she added.

“Such derogations must be given by member states individually,” Hipper said.

No date has yet been set for the meeting between Putin and Trump. Moscow has not given any indications about the Kremlin chief’s travel plans.

A senior EU diplomat said: “He needs to get permission to fly over certain countries. I don’t want to speculate on how this will go. But I’m happy I’m not his travel planner.”

Another potential hurdle for Putin is the fact that he currently faces a warrant for his arrest from the International Criminal Court — a warrant that Hungary, as signatory to the ICC, would theoretically need to enforce if he enters the country.

However, Hungary is unlikely to enforce the warrant.

“We will ensure that he [Putin] enters Hungary, has successful negotiations here, and then returns home,” Hungarian Foreign Minister Péter Szijjártó told a press briefing Friday.