On September 5, 1920, Polish Foreign Minister Eustachy Sapieha delivered a diplomatic note to the League of Nations asking it to intervene in the Polish–Lithuanian War. He claimed that Lithuania allowed free passage through its territory for Soviet troops and therefore violated its declared neutrality in the Polish–Soviet War. The next day Lithuania responded with a direct note to Poland in which Lithuanian Foreign Minister Juozas Purickis proposed to negotiate a demarcation line and other issues in Marijampolė. On September 8, during a planning meeting for what later was the Battle of the Niemen River, the Poles decided to maneuver through the Lithuanian territory to the rear of the Soviet Army. In an attempt to conceal the planned attack, Polish diplomats accepted the proposal to negotiate. The negotiations started on September 16 in Kalvarija, but collapsed just two days later.