Russian mercenaries in Donbas must stop fortification works that are being carried out during the ceasefire regime, said Ukrainian Foreign Minister Dmytro Kuleba.

"It has begun to act [the part on security in the Minsk agreements], but it has not been implemented yet. The ceasefire regime must be sustainable. The enemy continues fortification work, digging trenches - this should also be stopped. During the days of the truce, no one was wounded or killed in action, and this is a great achievement. But we must make sure that this is really a new reality. Not an imitation of it," the minister said in an interview published on the Gazeta.ua website on Thursday.