Russia general: Eastern Ukraine is Moscow's 'red line'
A former senior Russian military official has warned that any attempt by the Ukrainian government to take back eastern Ukraine by military means could lead to a full-scale Russian intervention.
Speaking to the BBC, the retired general, Evgeny Buzhinsky, said the movement of Ukrainian troops across the current ceasefire line might trigger a Russian response.
The warning comes as Russia continues the strengthening of its armed forces.
Bridget Kendall asked him what Russia perceived as the biggest threat.