The UK is hosting a closed meeting today of senior military leaders from the "coalition of the willing", as they draw up plans for a proposed peacekeeping force for Ukraine.
More than 20 countries are thought to be involved. Plans for a Western-led peacekeeping force for Ukraine are said to be moving to an operational phase.
Senior military officers from nations that make up the "coalition of the willing", led by Britain and France, are due to discuss how this would work in practice when they gather at the UK's Permanent Joint Headquarters in Northwood.
Armed Forces minister Luke Pollard said they want the coalition to be a "credible force" that would allow Ukraine to "enjoy a lasting peace" and "reconstitute and rearm".
But there remain some major obstacles.
Russian President Vladimir Putin has said Moscow will not tolerate the presence of any Nato member troops in Ukraine, regardless of their role.
The US is also proving reluctant to provide the necessary air cover that prospective members say they need.
