Ukraine natural resources in Ukraine include iron ore, coal, manganese, natural gas, oil, salt, sulphur, graphite, titanium, magnesium, kaolin, nickel, mercury, timber and an abundance of arable land. Despite this, the country faces a number of major environmental issues such as inadequate supplies of potable water; air- and water-pollution and deforestation, as well as radiation contamination in the north-east from the 1986 accident at the Chernobyl Nuclear Power Plant. Recycling toxic household waste is still in its infancy in Ukraine. From northwest to southeast the soils of Ukraine may be divided into three major aggregations: As much as two-thirds of the
Russian military intervention in Ukraine (2014–present) sphere of interest. Iulian Chifu and his co-authors claim that in regard to Ukraine, Russia pursues a modernized version of the Brezhnev Doctrine on "limited sovereignty", which dictates that the sovereignty of Ukraine cannot be larger than that of the Warsaw Pact prior to the demise of the Soviet sphere of influence. This claim is based on statements of Russian leaders that possible integration of Ukraine into NATO would jeopardize Russia's national security. After the collapse of the Soviet Union, both nations retained very close ties. At the same time, there were several sticking points, most importantly Ukraine's significant nuclear