Ukrainian President Volodymyr Zelenskyy visited the EU headquarters, Sunday, ahead of Monday's Washington summit.

He met with Ursula von der Leyen, President of the European Commission, who announced that European and NATO leaders will join the summit.

Vvon der Leyen called for "strong security guarantees to protect both Ukraine and Europe's vital security interests."

But she stressed that Ukraine must be able to uphold its "sovereignty and its territorial integrity".

"There can be no limitations on Ukrainian armed forces. Be it cooperation with or other third countries or assistance from other third countries."

The European leaders’ presence at Zelenskyy’s side, demonstrating Europe’s support for Ukraine, could potentially help ease concerns in Kyiv and in other European capitals that Ukraine risks being railroaded into a peace deal that Trump says he wants to broker with Russia.

It wasn't immediately clear whether all or just some of them would be taking part in the actual meeting with Trump.