The Russian President also reminded that Russia was ready to support Ukraine, share the risks with US, Europe and IMF.
"It has been four years - more than enough to mitigate those risks somehow. I don't understand this. If so — I give my permission to sue them [Ukraine]", Putin ordered.
Ukraine's debt totals $70 billion, some $40 billion of which the country owes to international money lenders.
In November, Russian President Vladimir Putin said Moscow was ready to allow Ukraine to miss the end of year deadline, provided it paid back $1 billion annually between 2016 and 2018.