MOSCOW — Russia’s economy felt the sting of the Ukrainian crisis Friday as a ratings agency cut its credit rating to near junk and Moscow hiked interest rates to keep its sliding ruble from fueling inflation.

The impact could get harder as the West threatens additional sanctions. Still, Russia is showing no signs of backing down, saying Friday that pro-Russian insurgents in Ukraine’s southeast will lay down their arms only if the Ukrainian government clears out nationalist protesters in Kiev, the capital.