Let's go live to our correspondent.

Or rather, are North America editor John So Paul, Who's there?

Just explain why this is happening.

John Clive.

It's a dramatic development.

You may be able to hear the sound of the rotor engines behind me because Marine one has just come in to land on the South Lawn of the White House.

And we understand that it is to take the president to Walter Reed Medical Center, about 15 miles north of here in area called Bethesda in Washington.

Now it's being stressed that this is a precautionary measure on.

I'm sort of struck by the similarities by what we heard a few months ago when Boris Johnson was admitted to hospital and people were saying it was a precautionary measure.

The big difference, I suspect, is that here in the White House there is a fully equipped medical center.

There are teams of doctors and nurses who are working 24 7 to assist in any medical emergency with the president, so they clearly think they need something that they cannot provide here on.

That will raise a lot of questions about whether it is mild symptoms that the president has or something more serious, and so everyone will await the next medical bulletin with interest.

In the meantime, I can hear the rotor blades of Marine One ready to ferry the President Toe Hospital.

But John, this does seem to developed incredibly quickly because it was only last night just before the president was diagnosed with Kobe, that he was giving television interviews.

Yeah, on DSO things doesn't it seems to follow a more serious trajectory than what you normally expect, which is that symptoms develop.

Their gradually worsened over a period of days.

But the White House is stressing.

Officials have confirmed this is what is going to happen, but they are stressing this is as a precautionary measure.

My question is, when you've got a fully equipped medical center here, why do you need to go to war to read?

But maybe there is a very innocent explanation for that attack moment.

Of course, the White House is trying to play this down.

Is not trying to get people to alarmed.

I think it's interesting and telling that they waited for the markets to close before making this clear that this is what they were going to do.

But as we speak, the president appears to be on his way to the very famous military hospital in the north of Washington.

Okay, John.

Thank you for that update, John.

So Paul there and North America Editor.