Putin's chief spokesperson: 'We have our red lines'

President Putin's chief spokesman, Dmitry Peskov, has told the BBC that Russia has red lines in Europe that it will not allow to be crossed, and it will intensify its response if its national interests are challenged.

Tensions have been building again between Russia and the West after it was reported that Russian fighter aircraft and bombers had stepped up their probing of Nato airspace.

Russian troops and equipment were reported to have crossed into eastern Ukraine as well, and President Putin was given sharp warnings by world leaders at the G20 summit.

Mr Peskov was speaking in a rare interview in Moscow with the BBC's World Affairs Editor, John Simpson.