Tillerson left to pick up the pieces from Trump's pronouncements
The US Secretary of State is meeting Foreign Secretary Boris Johnson in London as he tries to ease Anglo-American relations.
Monday 22 January 2018 10:34, UK
The American government may be in shutdown but that hasn't stopped it sending two of its most senior officials on forays abroad.
Both face severe challenges thanks to recent pronouncements by their boss, Donald Trump.
Vice President Mike Pence is touring the Middle East on a trip that has been complicated by his President's contentious decision to recognise Jerusalem as the capital of Israel.
Key figures are either refusing to meet Mr Pence, or giving him lectures on the region's politics when they do instead.
US Secretary of State Rex Tillerson is in London, the first stop of a tour of Europe.
His main aim: to push for a harder line on Iran and commitments from European allies to "fix" the nuclear deal with that country.
This would be challenging enough.
Mr Trump has threatened to remove America's support for the deal unless it is altered.
The President says he believes it is a bad agreement but has thus far stopped short of scuppering it.
The deal removed some sanctions against Iran in return for measures that verifiably curtail its alleged nuclear weapons programme.
If Mr Trump walked away from the deal, his generals have warned, it would give the Iranians the green light to go hell for leather to make the bomb.
So instead the President says it should be revised to deter Iran from meddling in other countries and from continuing a ballistic missile programme.
There are two problems with that position.
Firstly, the deal was deliberately designed only to cover nuclear weapon development, not other issues.
Secondly, the countries that negotiated it along with America have made it clear they do not believe it should or can be renegotiated.
When Mr Tillerson meets Foreign Secretary Boris Johnson we will likely hear plenty of tough talk about Iran's conduct, but progress towards a revised nuclear deal will be problematic to say the least.
US-British relations have been complicated due to the President's bizarre interventions on Twitter.
His apparent endorsement of a far-right British group on Twitter plunged relations to a new low when Prime Minister Theresa May was forced to express her disapproval.
As an apparent sign of his disgruntlement at that, Mr Trump has ruled out coming to London to open the new US embassy.
Mr Tillerson, who is reported to have called the President a "moron" previously, is left to pick up the pieces.
It would be quite a task even for a seasoned diplomat.
He has precious little experience in the field, having spent most of his life in the oil industry.