US President Joe Biden invited his Ukrainian counterpart to Washington this week because he determined the war in Ukraine had entered a new stage, Strategic Communications Coordinator at the National Security Council John Kirby said on CNN.
"The President really believes that as we approach winter, as we enter ... a new phase in this war, Mr. Putin's aggression, that this is a good time for the two leaders to sit down face to face and talk," he said.
The talks are expected to focus on the continued U.S. military and economic assistance along with sustaining sanctions against Russia and supporting the Ukrainian people.
John Kirby said the presidents would also discuss how the war might end, a sensitive topic that is the subject of some disagreement among Western leaders.
"I have no doubt they are going to talk about President Zelenskyy's notion of a 'just peace' and what he said.
"Mr. Putin it's obviously not interested in diplomacy right now. Quite the contrary. He's interested in killing more Ukrainian civilians," added Kirby.
Today Volodymyr Zelenskyy is making his first foreign visit since the full-scale invasion. Bilateral talks with Biden, a speech to Congress and a final briefing are expected.
The US is to announce a new package of military aid to Ukraine worth about $1.8 billion, including Patriot air defence systems.