Posted on 14 March 2018
Dr James Rogers from the University of York's Department of Politics explains that what happens next could be crucial for UK and US relations:
''The prime minister has stated that it is 'highly likely' Russia was involved in the use of a Soviet-made nerve agent on a former Russian spy.
"If true, this is a reckless use of a military-grade chemical agent in a public place and on UK soil. Its use also raises broader political issues which need to be monitored carefully.
"After being accused of 'weakness', May gave Russia an ultimatum. This is likely to escalate tensions. Yet, there is a problem here. Where there was initially strong American support for the UK cause, since Tillerson has been sacked, US policy on the issue has become less clear.
"How May (and Trump) act now will not only have important implications for actions taken against Russia, but it could also reveal something extremely interesting about the extent of the UK government's relationship with the Trump White House.
"Substantial measures have been implemented by May, with the suspension of all planned high level bi-lateral contacts between the UK and Russia being among the most severe. Russia has accused the US of 'playing politics', yet it will be interesting to see how US perceptions evolve over the next few days as pressure mounts on all sides."