Will Chalk

McMaster, who served in the first Trump administration, and he called President Trump's remarks insulting.

That sentiment was echoed by the former US ambassador to NATO, Kirk Volker, who said that the President simply didn't know what he was saying.

Well, there have been numerous calls for an apology, but that's not traditionally Donald Trump's style, is it?

Not really, and I think the chances of that are slim to non-existent.

This is a president who is given to shooting from the hip, who doesn't relish being seen as weak, and who doesn't like to back down.

And over the course of the last week, he's railed against supposed allies and friends on a variety of different fronts, not least over his desire to acquire Greenland, reserving particular disdain for NATO, claiming that fellow allies

member nations haven't been pulling their weight and floating the view that whilst the United States will be there for NATO in times of crisis, NATO may well not be there for the United States.

The fact of the matter, of course, is that the one and only time that NATO has ever enacted Article 5 was after the attacks of 9-11, and the alliance came resolutely to the support of the US.

And in response to the White House's contention that it was President Trump who forced NATO

that enhanced commitment in NATO defence spending.

There are many, I think, who would argue that Russia's invasion of Ukraine did as much, if not more, to focus mines than did the chiding of President Donald Trump.

But there's a feeling, I think, that the President's latest comments have

crossed a line, prompting the very strong suggestion that he apologise.

And that, of course, could always have completely the opposite effect, giving what we know about this president, prompting Mr Trump effectively to double down and giving rise to a new war of words with allies such as the UK.

David Willis speaking to me from Los Angeles.

Russia, Ukraine and the US have held their first trilateral talks to try and bring an end to the war.

Negotiations in Abu Dhabi will resume on Saturday and the issue of territory is very much at the top of the agenda.

Our correspondent Sarah Rainsford has been following developments from Kiev.

The format for these talks is new.

The delegates are senior.