Britain and the US - caught napping in 2014 when Russia annexed Crimea, despite initially denying any involvement - appear determined this time to expose any new Russian attempt to use lies and deception to mask or create an excuse for a further invasion.

A key tactic to combat or deter such activity is to make it public before it happens.

But using information as a weapon successfully - such as by revealing the "truth" to expose a "lie" or some "deception" - requires skill and a coherent strategy, especially when going up against the Kremlin, which knows this battlespace well.

Russian officials, spy agencies and state-run media channels are well-rehearsed at deploying fake news or false equivalences to discredit or undermine an opponent, flooding their version of events online, on TV, in newspapers or in public statements.

For example, Vasily Nebenzya, Russia's ambassador to the United Nations, recently drew an analogy between US warnings about the threat posed by Moscow to Ukraine and flawed US claims about weapons of mass destruction in the run up to the 2003 Iraq war.

The underlying message was clear: the United States was wrong then and is wrong now.

Moscow's goal, in the case of Ukraine and wider European security, is to use information to influence domestic and global opinion in their favour and attack whatever the West alleges.

For Britain, the United States and other NATO members, the aim seems to be to deny Russian President Vladimir Putin the ability to operate in the shadows again by calling out details of what their intelligence agencies believe is being planned.

But not only do Western allies need to contend with the inevitable Russian dismissal of whatever allegation they make, they also need to be able to demonstrate to friendly governments, the world's media and the wider public that their claims are based on facts.

Read more: Three new signs of Russian Invasion plans

Without such evidence - notwithstanding the sensitivities of revealing details about declassified intelligence - they stand less of a chance of defeating Russian denials and risk doing more harm to their own credibility than to their adversary's.

Just take an exchange on Thursday between a US Statement Department spokesman and a highly experienced diplomatic correspondent during a briefing on American allegations that Russia was plotting an elaborate, false-flag operation to justify a further invasion of Ukraine.

Matt Lee, the Associated Press reporter - speaking for journalists globally - made the point that these assertions were being delivered with zero evidence other than the word of US officials who have on occasion in the past been wrong.

"I am sorry you are doubting information in possession of the US government," Ned Price, the spokesman, said.

He explained that Washington was making the intelligence - in the form of his comments - public to deter Moscow from carrying out the alleged scheme.

The plot involved producing a video, with real corpses, of a staged attack against a Russian target to frame Ukrainian forces - creating a pretext for war.

"If the Russians don't go forward with this, that is not ipso facto an indication that they never had plans to do so," Mr Price said.

Mr Lee responded: "But then it's unprovable, my god."

Footage of the exchange on Thursday went viral, with millions of views.

Hardly the focus Washington would have wanted when it chose to release the intelligence - but a good example of how such claims, regardless how credible, might land when not supported by verifiable evidence.

Then again, even evidence of a threat won't be enough to persuade everyone.

The US and the UK have been the loudest voices warning of a possible further invasion of Ukraine as Russia openly masses more than 100,000 forces and weapons within striking distance of its neighbour's borders.

Yet the Kremlin continues to brush off Western warnings of a possible attack as "hysteria" and insist no such aggression is being planned.

It has almost reached a point where President Putin would be doing British and US spy agencies a favour by invading and proving their warnings right.

In fact, some analysts note he could simply choose to inflict harm on their credibility by continuing to hold fire - creating an impression of "the boy who cried wolf" even though the wolf is very real.

A glance at responses to a tweet I posted on the information contest raging over Ukraine gives a sense of how pro-Russia accounts are exploiting the doubt in western claims.

The tweet mentioned the alleged fake video plot and also comments from a Ukrainian minister about how the US and British tactic of calling out suspicions about a possible Russian invasion was "ruining" Moscow's plans.

Dmitry Polansky, Russia's deputy ambassador to the United Nations, responded: "First they create a hype about alleged Russian plans for aggression that existed only in their troubled imagination, then promote info about non-existent video as its proof and now they take credit for ruining our never-existing plot. Solo Delirium politics? KeepCalmAndBlameRussia."

There were plenty of anonymous reactions too.

One Twitter account holder wrote to me: "Did they show you some evidence? Are you a journalist or a stenographer?"

Another one remarked: "I think you mean 'US spread fake invasion disinformation & when nothing happened suddenly claimed they've thwarted fake invasion because they made it public'. So you're either a moron or complicit."

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On the flip side, however, if Russia is plotting a false provocation to justify an invasion and does actually carry out that threat - the world will have been forewarned.

Presumably British and US officials have weighed up this potential scenario and decided it is worth the heat they are taking for their currently un-evidenced allegations.