How did the Mongols disrupt international relations?
Actually, aside from disruptive military campaigns from the Adriatic to Palestine to Japan, the Mongols probably did more to enhance international relations than they they did to disrupt them. They maintained diplomatic contact with Western Europe, India, and Korea. They allowed merchants, diplomats and missionaries to travel freely through their Empire, and even provided protection for them on the silk roads. They frequently fought among themselves, but maintained peaceable relations with other areas to the extent this was possible. They also insisted on proper diplomatic protocol. When the Shah of Persia had a Mongol ambassador sent there to open diplomatic relations murdered, Genghis Khan had the Shah murdered in retaliation. A number of Christian nations in Europe sent ambassadors to the Mongols, asking for assistance in fighting the Muslims; and the Mongols in turn sent Nestorian monks as ambassadors to Italy and France.
China and Europe actually became connected by trade for the first time during Mongol rule, as their protection of merchants and other travellers on the silk roads made uninterrupted trade possible. So rather than disrupting international relations, the Mongols actually encouraged and enhanced them.