Why should Russia explain what the UK is doing with the toxic agents it is making at Porton Down?
That is what I suspect too.
Good question.
President Trump would do well to overfly londonistan, have the pilot wag AF1 wings over the British parliament and the insulting blimp over it and go on to check out the Scottish golf courses as he radios Theresa May that he might reschedule a visit when her and other government leaders stop the nonstop attacks and the Brits can get a handle on their rogue nerve agents that seem to sit all over the country waiting for someone to touch it. Going into that hostile atmosphere with blatant verbal/visual constant insults in the hosting country's government for a State visit is just unwise by any measure.