The heaviest fighting took place on 18 May, when the Armenians captured Nakhchivan's exclave of Karki, a tiny territory through which Armenia's main north–south highway passes. The exclave presently remains under Armenian control. After the fall of Shusha, the Mütallibov government of Azerbaijan accused Armenia of moving to take the whole of Nakhchivan (a claim that was denied by Armenian government officials). However, Heydar Aliyev declared a unilateral ceasefire on 23 May and sought to conclude a separate peace with Armenia. Armenian President Levon Ter-Petrossian expressed his willingness to sign a cooperation treaty with Nakhchivan to end the fighting and subsequently a cease-fire was agreed upon.