Russia has yet again ignored Donald Trump’s bid to hold a summit between Vladimir Putin and Volodymyr Zelensky and said attempts to resolve security issues for Kyiv without Moscow’s participation was a “road to nowhere”.

Special U.S. envoy Steve Witkoff says Russian leader Vladimir Putin agreed to allow the U.S. and Europe to offer Ukraine a security guarantee resembling NATO's collective defense mandate.

General Christopher Donahue, commander of U.S. Army Europe and Africa, said allies could seize Kaliningrad "in a timeframe that is unheard of."

Donald Trump said the US would help arrange European security guarantees for Ukraine if peace could be agreed with Russia, as he pledged to set up a meeting between Volodymyr Zelenskyy and Vladimir Putin.

The push for a bilateral meeting comes after the US president met Putin in Alaska last week, and welcomed seven European leaders and Zelensky to the White House on Monday. Trump admitted the conflict was "a tough one" to solve and conceded it was possible the Russian president was not interested in ending hostilities.