B/P: "I think at the time..."
Assuming that "thinking" could actually be one of your strengths compare that to mmafr's extremely prudent statement (5 minutes before yours): "....avoid unnecessary speculation".
b/p: Whether you like it or not - you are the most popular negative speculator on this BB. So you may want to take mmafr's proposal into consideration.
Barclays - if I may jump in here:
If you have a contract based claim, the respective contract will determine the jurisdiction and the applicable law.
I assume there is no contractual basis and - quite frankly - even if there were Governments never agree to alien jurisdictions.
So - whichever way you look at it: PM would have to take action in Mongolia. Good luck with litigating against a Government in its own country!