Critical week for US's future in Ukraine-Russia talks, Rubio says

This week will be "very critical" for Russia-Ukraine war talks as Washington decides if it is an "endeavour that we want to continue to be involved in", US Secretary of State Marco Rubio said.

Rubio told US media that Donald Trump hasn't imposed new penalties on Russia because he still hopes diplomacy can end the war.

It comes after Trump held a brief meeting with Ukrainian leader Volodymyr Zelensky at the Vatican before Pope Francis' funeral on Saturday.

Updating reporters on Sunday, Trump said he believes Zelensky is willing to give up Crimea to Russia as part of a peace deal - despite Kyiv's previous rejections of any such proposal.

Speaking to NBC's Meet the Press programme, Rubio said: "There are reasons to be optimistic, but there are reasons to be realistic.

"We're close, but we're not close enough. Throughout this process, it's about determining, do both sides really want peace and how close are they or how far apart they are after 90 days of effort here... that's what we're trying to determine this week."

Addressing the prospect of imposing penalties on Vladimir Putin, Rubio said: "The minute you start doing that kind of stuff, you're walking away from it."

Over the weekend Trump questioned whether the Russian president wants to "stop the war" against Ukraine.

"It makes me think that maybe he doesn't want to stop the war, he's just tapping me along, and has to be dealt with differently, through "Banking" or "Secondary Sanctions":[]}