MOSCOW (Reuters) -North Korean leader Kim Jong Un inspected a Russian fighter jet factory that is under Western sanctions on Friday, part of a visit Washington and its allies fear could strengthen Russia's military in Ukraine and bolster Pyongyang's missile program. Russian President Vladimir Putin had discussed military matters and deepening cooperation with Kim when they met in a summit on Wednesday. South Korea and the United States said on Friday that military cooperation between North Korea and Russia was a violation of U.N. sanctions and that the allies would ensure there is a price to pay.