MOSCOW, Oct 9 (Reuters) - Authorities declared a state of emergency on Wednesday in a western region of Russia where Ukraine said it had struck a weapons arsenal overnight. The local branch of the Emergencies Ministry said an emergency had been declared in one district of the Bryansk region following "detonations of explosive objects". Ukraine's military said it had struck an arsenal storing ammunition for missiles and artillery weapons, including those delivered from North Korea, as well as guided aerial bombs. Russia and North Korea have denied weapons transfers between the two countries but vowed to boost military ties. The...