Washington, United States (AFP) February 27 - The EU's top diplomat said Thursday that NATO offered the best security guarantee for Ukraine, accusing President Donald Trump of falling for a Russian narrative by closing the door.

In an interview with AFP on a visit to Washington, Kaja Kallas also warned that the Europeans would not be able to assist in an eventual ceasefire deal in Ukraine's three-year conflict with Russia unless they are included by Trump, who has reached out directly to Russian President Vladimir Putin.

Kallas, a former prime minister of frontline state Estonia, said NATO countries have never attacked Russia which instead was "afraid of democracy."

"Why are we in NATO? It is because we are afraid of Russia. And the only thing that really works -- the only security guarantee that works -- is NATO's umbrella," she said.

Russia cited potential Ukrainian membership in NATO as a reason for its invasion three years ago. Putin has since questioned the historical legitimacy of Ukraine as a separate country from Russia.

Trump, who broke Putin's isolation with a telephone call earlier this month, said Wednesday that Ukraine can "forget about" joining NATO in any settlement, explaining: "I think that's probably the reason the whole thing started."

"These accusations are totally untrue," Kallas said when asked about Trump's remarks. "That is the Russian narrative that we should not buy."

"My question is, why we should give Russia what they want on top of what they have already done -- attacking Ukraine, annexing territory, occupying territory, and now offering something on top of it," she said.

"Consider here in America that after 9/11 you would have sat down with Osama bin Laden and said, 'OK, what else do you want?' I mean, it's unimaginable."

Russia has insisted that the United States promised at the end of the Cold War not to expand NATO, the US-backed alliance.

Some US diplomats from the era deny the account, although some have also cautioned that Ukrainian membership in NATO would be a red line for Moscow.

- 'Europeans need to be on board' -

Trump has been dismissive of NATO, saying it is unfair for the United States to offer security to wealthy allies that mostly pay less on defense in relation to the size of their economies.

Trump, who is expected to sign a deal Friday with Ukrainian President Volodymyr Zelensky to secure much of Ukraine's mineral wealth, has refused to offer US security guarantees to Ukraine and said it was up to Europeans.

Kallas said that in any deal on Ukraine, "Europeans need to be on board."

"We need to be part of those discussions. I think without it we can't provide anything."

Trump, in his remarks at the White House on Wednesday, also said that the European Union was set up to "screw the United States" as he plans tariffs to close a trade deficit.

The now 27-nation bloc was created three decades ago as part of efforts to avoid further conflict after two world wars ravaged the continent.

Kallas called Trump's remarks "surprising" and said the two sides long had common values.

The Trump administration has also slashed the vast majority of US foreign assistance.

While the United States was the largest donor in the world in dollar terms, the European Union as a whole provides more and a number of northern European countries provide more as a share of their economies.

Kallas said Europe will "not be able to fill the gap that America is leaving" but that the world is "looking to us" on what more it can provide.

"I feel that we need to also increase our geopolitical power," she said.

"If America is turning inwards, Europe is turning outwards."