EVER since the start of the crisis in Ukraine, I've been firmly of the belief that pro-Russian separatist aspirations in some eastern cities of the country make for the most dangerous flashpoints.

In Crimea's case one always sensed that the Ukrainian government would forfeit - albeit reluctantly - a region in which Russia has historically held sway.

The West too, realised that short of throwing its diplomatic rattle out the cot, Crimea's annexation by Russia was something they would just have to live with.

Should Moscow's territorial ambitions and military presence extend to rump Ukraine though, that would present an altogether different problem.

Tensions have risen dramatically in the mainly Russian-speaking east since the overthrow of Ukraine's Moscow-backed President Viktor Yanukovich and the installation of a new pro-European government, that claims a Russian-led plan is under way to dismember Ukraine.

Hardly surprising then that in Kiev, Washington and western European corridors of power, alarms bell have been ringing these last few days as pro-Russian activists occupied official buildings in the eastern Ukrainian cities of Luhansk and Donetsk.

Giving added cause for worry is the fact that massed along Ukraine's borders are 40,000 Russian troops "not training but ready for combat," according to Nato General Secretary Anders Fogh Rasmussen.

As the tension has grown, so too have diplomatic efforts to resolve the standoffs in Luhansk and Donetsk, with the Ukrainian government insisting it will not prosecute pro-Russian separatists who seized the buildings if they surrender their weapons and disperse.

Yesterday, on a wider level, the diplomatic pressure intensified. Russia was suspended from the parliamentary assembly of European human rights watchdog the Council of Europe over Ukraine and Crimea.

In turn, Russian President, Vladimir Putin, told European leaders that Ukraine's growing gas debts to Moscow could threaten supplies to Europe. The Kremlin also upped-the-ante by saying that any deployment of Nato forces in regions bordering Russia would violate an agreement between the alliance and Moscow.

Such Russian muscle flexing will only serve to embolden those armed pro-Russian separatists, who yesterday strengthened barricades around buildings in Luhansk and Donetsk with barbed wire and sandbags, insisting that they would not leave unless the Ukrainian government also agreed to hold a referendum to boost the regions' independence.

Faced with how best to respond, Ukraine's government finds itself in a tricky tactical position.

According to some reports, yesterday that response was taking the shape of Ukrainian troops and tanks grouping around Donetsk. This with only hours remaining for Kiev's threatened deadline to use force against those occupying government buildings there.

Any armed storming of these buildings could easily provoke a strong response from Moscow, which has reserved the right to send troops in to protect Russian speakers.

Where all this goes from here depends on whether cool or hot heads prevail and diplomacy rather than military action wins the day. Worryingly, what until now has largely been a war of words, has suddenly turned more conspiratorial, belligerent and threatening.

Earlier this week a speech by US Secretary of State John Kerry, reiterated Washington's growing concern that the unrest raging in eastern Ukrainian cities might conveniently provide Mr Putin with an excuse for an armed incursion there.

Not to be outdone, the Kremlin put around a conspiracy story of its own, with a statement from the Russian Foreign Ministry saying that the private American security contractor Greystone, had joined forces with the far-right Ukrainian group Right Sector to neutralise pro-Russian activists in eastern Ukraine.

The problem with both these conspiracies is not just that there is no real evidence to back them up, but that both only help fuel what is already an incendiary situation that requires only the tiniest spark to set the region alight with conflict.

Next week the EU, Russia, US and Ukraine are due to meet for talks on the crisis. These talks cannot come quickly enough, for these are dangerous days indeed in Eastern Ukraine.