Definition: Generate an appropriate title for the given text. The generated title must be short and include the main topic of the text. The preferred titles are under fifteen words.
Input: Arseniy Yatsenyuk told the UN General Assembly that Russian troops were still operating in eastern Ukraine. Earlier, US President Barack Obama said sanctions could be lifted if Russia supported a ceasefire between Ukraine and separatist rebels in the east. Russia denies arming the rebels and sending Russian troops to Ukraine. Russia annexed Ukraine's Crimea southern peninsula in March - a move condemned by Ukraine and the West. The European Union and the United States later imposed sanctions against Russia over its role in the Ukraine conflict. UN officials say 3,245 people have been killed since fighting between Ukrainian troops and pro-Russia separatists began in April. A shaky ceasefire has held since 5 September, and the two sides have since agreed to set up a 30km (19 miles) buffer zone. "We ask our partners not to lift sanctions until Ukraine takes control of its entire territory," Mr Yatsenyuk said. "Crimea was, is and will be a part of Ukraine." "Russian troops are deployed in the east of Ukraine," he said. "We urge Russia to pull back its forces... and to start real talks." "Every day, despite the ceasefire, we are losing Ukrainian soldiers, we are losing civilians." He told Russia: "You can win the fight against the troops, but you will never win the fight against the... united Ukraine nation." Earlier, Mr Obama criticised Russian actions in Ukraine, but said that if Russia took the path of peace, "then we will lift our sanctions and welcome Russia's role in addressing common challenges". On Wednesday, Nato said it observed a "significant" withdrawal of Russian troops from eastern Ukraine, but added that some forces still remained there. Minsk memorandum on ceasefire: Key points

Ukraine warns West against lifting Russia sanctions