sentences:  At the end of December the company issued a press release on cooperation with Federal Environmental, Industrial and Nuclear Supervision Service of Russia (Rostekhnadzor) and Norilsk Nickel signed a protocol of cooperation with regard to industrial safety and environment protection in the development of the Company's operations.In 2010, Vladimir Putin visited Norilsk and complained about the pollution, threatening a “significant increase in environmental fines” if the company did not modernise its plant.By 2013, owner Vladimir Potanin had begun to invest in environmental measures.