Invited by the legitimate government  President Yanukovych is Ukraine’s legitimate President. He is therefore perfectly at liberty to allow Russian troops into his country to keep the peace in much the same way as countries around the world welcome US troops on their soil as protection from external threats or UN peacekeepers to keep the peace domestically. Yanukovych in a letter to Putin called “on the President of Russia, Mr. Putin, asking him to use the armed forces of the Russian Federation to establish legitimacy, peace, law and order, stability and defending the people of Ukraine.” [1]  [1] ‘Yanukovich sent letter to Putin asking for Russian military presence in Ukraine’, RT, 3 March 2014