What is happening on the ground in east Ukraine?
Tensions have increased after Russian-backed separatists opened fire across the line of control with Ukrainian forces, hitting a nursery school and injuring three people. The west says Moscow may be seeking a pretext to openly intervene in the fighting in defence of the separatist territories that it controls. Russia has amassed a force of nearly 150,000 soldiers in the border regions near Ukraine, and the US has warned that an invasion could be “imminent”.