Japanese nonlife insurers have suspended undertaking new contracts entirely for domestic firms that operate in Russia, affected by Moscow’s countermeasures against economic sanctions following its invasion of Ukraine, sources close to the matter said Saturday. Insurers such as Tokio Marine & Nichido Fire Insurance Co. will also not renew existing contracts after their terms have expired, the sources said, in a move that could leave Japanese firms uninsured or facing higher premiums by entering into new agreements with local insurers. The suspension comes after Russia designated Japan as an “un…