A new front line of conflict is taking shape in Europe, with enhanced levels of risk that raise questions about whether NATO will, or even can, respond effectively.

Having invaded Ukraine and deployed its troops in a compliant Belarus, Russia has suddenly extended its military power to the borders of several NATO countries, including the Baltic nations.

If Russia succeeds in taking over Ukraine and keeping bases in Belarus, as many experts now expect, its forces will extend from the borders of the Baltics and Poland to Slovakia, Hungary and northern Romania, making it significantly harder for NATO to defend its eastern flank.