MOSCOW (Reuters) – Russian-backed rebels in eastern Ukraine accused Kyiv government forces of firing artillery and mortars in three incidents on Friday, the Interfax news agency reported. Kyiv and the rebels blamed each other for escalating tensions after artillery and mortar attacks on Thursday, prompting fears that Russia, which has massed over 100,000 troops near Ukrane’s borders, could get involved. The Kremlin said on Thursday it was “deeply concerned” with the flare-up in Ukraine and was watching the situation closely. The United States said Russia was looking for a pretext for war. Acco…