Reassurance, not peacekeeping: What Ukraine coalition force will and wont do

The potential Western troop deployment to Ukraine being discussed in London should be described as a "reassurance force" rather than a "peacekeeping force", defence and diplomatic sources say.

Currently dubbed the Multinational Force Ukraine or MFU, it would be sent to the country to cement any ceasefire and encourage long-term confidence in the country.

The focus would be on providing Ukraine with air cover to keep its skies safe and a naval presence in the Black Sea to encourage trade.

The deployment of so-called "boots on the ground" - probably about 20,000 strong - would in terms of size not be big enough to enforce any peace.

Instead, the troops - provided by a so-called "coalition of the willing" - would most likely be deployed to protect cities, ports and major energy infrastructure.

One option being considered is that the MFU might not operate in the east of Ukraine near the front line to try to reassure Russia it poses no offensive threat.

Russian President Vladimir Putin and the Kremlin have said repeatedly they would not agree any ceasefire if European and other forces were deployed to Ukraine.

The sources say any multinational operation in Ukraine would not be a "peacekeeping force" and should not be described as such.

Peacekeeping forces - under the aegis of either the United Nations or Nato - traditionally are impartial, operate with the consent of both parties and use force only to defend themselves. The multinational force being discussed would very much be on Ukraines side, there to help deter future Russian aggression.

At the moment, it is not expected that the multinational force on the ground would monitor any ceasefire. That would be done by Ukrainian troops on the frontline and Western surveillance assets in the air and space.

The sources also say the coalition troops would not be deployed to provide a so-called "tripwire force" - meaning a force smaller than that of the opponent, designed to deter an attack without triggering escalation - if Russia resumed its invasion of Ukraine.

They say the military impact of any allied deployment of about 20,000 troops would be limited compared to the number of troops on either side of the front line.

Ukraine has almost a million military personnel, Russias army is even larger.

Much of the focus of Thursdays discussions is on how best any international force can provide Ukraine with assets it does not have, especially capability in the air.

So, there will be discussions about which countries can provide warplanes to keep Ukraines skies safe during a ceasefire.

There will also be discussions about how to make the Black Sea safe for shipping. That may involve two components: how best to keep shipping lanes clear of mines and what kind of naval task force could provide a security presence in the sea.

The key uncertainty is whether the United States would provide any air, satellite or intelligence cover for any European force on the ground.

The US has thus far said it would not be willing to provide any military "backstop".

The European strategy for now is to stop asking the US and instead organise the best force and capability it can to ensure the security of Ukraine in the future. Once the details are agreed, then the UK, France and others would see if the European offer was substantial enough for the US to have a change of heart and agree to play some kind of role.

What all this planning depends on, of course, is some kind of ceasefire being agreed in Ukraine.

While the US remains optimistic, many in Ukraine remain sceptical that Russia even wants to end the fighting.