From the article:

Frantic efforts to restore gas supplies to millions of European consumers failed yesterday after Russia refused to turn the pipeline back on in its showdown with Ukraine.

A European Union plan to send monitors to both countries, agreed in principle by Moscow and Kiev as a way of breaking the deadlock between them, faltered at the 11th hour when Russia demanded that its own inspectors should be sent to Ukraine alongside independent experts. Last night the EU decided to send its monitors to Ukraine anyway, in the hope of persuading Russia to re-open the taps.

The row has left 12 countries without deliveries in freezing temperatures and meant hundreds of schools and factories have closed to conserve fuel. Hundreds of thousands of people across the Balkans, the worst-affected region, found themselves without heating and some hospitals were forced to close in Serbia as temperatures dipped below minus 10C (14F).

A senior US diplomat warned that Nato might have to intervene to help alliance members such as Bulgaria and Romania if the crisis drags on. “There is a commercial dispute at the heart of this, but this also has political overtones [becasue] we have seen Russia over time using such events to gain political leverage,” Kurt Volker, the US Ambassador to Nato, said.

Read the full article here.

There is a great series of maps and graphics that clarify this situation here.

Thanks to Aesthetic Traditionalist for pointing out this article.