Ukraine’s Foreign Ministry said on Monday that Mongolia’s failure to arrest visiting Kremlin leader Vladimir Putin, wanted on an international warrant, dealt a severe blow to the international criminal law system.

Putin arrived in Mongolia on Monday for talks likely to focus on a new gas pipeline connecting Russia and China.

An International Criminal Court arrest warrant issued last year against Putin obliges the court’s 124 member states, including Mongolia, to arrest the Russian president and transfer him to The Hague for trial if he sets foot on their territory.

Ukrainian Foreign Ministry spokesperson Heorhiy Tykhyi said Mongolia’s failure to detain Putin was "a heavy blow to the International Criminal Court and the system of criminal law.