Hastily declared ceasefires can be fragile - why Iran and Israel might soon resume conflict

Ceasefires that are suddenly declared tend to be pretty fragile.

Stable ceasefires usually require a lot of preparation so that everyone on both sides knows what is supposed to happen, and - more importantly - when. And they normally agree on how it will be monitored so one side cannot seize a quick advantage by breaking it suddenly.

Israel-Iran live updates: Trump swears live on camera as he rages at Israel and Iran Without such preparations, and sometimes even with them, ceasefires will tend to be breached - perhaps by accident, perhaps because one side does not exercise full control over its own forces, perhaps as a result of false alarms, or even because a third party - a guerrilla group or a militia, say - choose that moment to launch an attack of their own. The important question is whether a ceasefire breach is just random and unfortunate, or else deliberate and systemic - where someone is actively trying to break it.

Either way, ceasefires have to be politically reinforced all the time if they are to hold. Read more from Sky News:Israel-Iran ceasefire hopes drive down oil and gas costs'They don't know what the f*** they're doing': Trump rages All sides may need to rededicate themselves to it at regular intervals, mainly because, as genuine enemies, they won't trust each other and will remain naturally suspicious at every twitch and utterance from the other side.

This is where an external power like the United States plays a critical part. If enemies like Israel and Iran naturally distrust each other and need little incentive to "hit back" in some way at every provocation, it will take US pressure to make them abide by a ceasefire that may be breaking down.

Appeals to good nature are hardly relevant in this respect. An external arbiter has to make the continuance of a ceasefire a matter of hard national interest to both sides.

And that often requires as much bullying as persuasion. It may be true that "blessed are the peacemakers"..