What we should make of CIA boss's secret trip to Moscow

President Donald Trump said John Ratcliffe's trip to Russia was a "semi-routine" visit but there is nothing routine about the CIA chief making a secret, 10,000-mile return dash to Moscow.

Ratcliffe met Russian intelligence officials on Tuesday - notably his opposite number in Russia's overseas spy agency, Sergei Naryshkin - after arriving unannounced on a US military plane, the Kremlin confirmed.

It's been nearly five years since his predecessor William Burns made this trip and that was at a similarly tense time, just as Russia was drawing up plans to invade Ukraine. So, this is probably serious.

In the absence of any official US comment on the reason for the mission, it is being widely reported Ratcliffe's trip was to warn Moscow not to escalate in relation to the stalemate in Ukraine - possibly by taking action against Nato members.

One US official told Politico that the "meeting was primarily to warn Russia against any escalatory action against the Baltic states".

The UK is also in Russian crosshairs. On Thursday, a foreign ministry spokeswoman said Russia could strike British military targets as retaliation for Ukrainian strikes on Russia using British missiles.

And a drone carrying an explosive which was discovered at an airport in the German city of Leipzig was probably Russian, security experts have said.

News of Ratcliffe's visit follows reports of US intelligence assessments that President Vladimir Putin was planning a limited assault on a Nato ally.