Shaky ceasefire masks simmering aggression and deep distrust over Ukraine

Since a ceasefire was declared on Sunday, the commander of one of the Ukrainian forces' most well-known irregular battalions has been sitting in his office, monitoring the truce from a base just minutes from the front line. And it is making him itch.

Sergey Melnichuk, a member of parliament, is in charge of the Aidar battalion, a unit of volunteer troops with a checkered history of aggressive behaviour toward civilians - and a reputation for being one of the fiercest attack forces in the pro-Kiev operation.

The battalion operates in the area around Luhansk, about 100km northeast of Debaltseve, where pro-Russian rebels have all but surrounded about 5,000 Ukrainian troops, shelling has continued from both sides, and the ceasefire has been largely ignored. But to Melnichuk, the comparative quiet in Shchastya is more dangerous than the fighting - and his unease is an example of how, even where the ceasefire is holding, the front line may not be as peaceful as it seems.

"The longer this goes on, the more we lose," Melnichuk said. "Why are we sitting here and waiting to be struck? We should attack. We should reply."

The Aidar battalion is just one of several affiliated volunteer groups fighting alongside the Ukrainian military. They have built their reputations through regular appearances in the conflict's hottest zones.

Though they often work with regular members of the military, these groups maintain an element of independence. Now they are struggling to keep that in check as they adhere to a ceasefire many believe is undermining the whole operation.