GROZNY, Nov 9: Russian forces continued to bombard breakaway Chechnya on Tuesday, as Moscow rejected renewed pressure from Washington to halt its military offensive. But the first snows of winter and heavy fog forced the Russian airforce to cut back on bombing missions across Chechnya, marking a difficult new phase in the two-month-old Russian campaign against the rebel republic.``The Chechen problem is an internal Russian matter. There has never been a question of conducting a war against the Chechen people, but a military operation to crush the sources of terrorism,'' said deputy Chief of staff in the Kremlin administration, Igor Chabdurasulov, cited by ITAR-TASS.Monday, the United States accused Russia of violating international agreements on the conduct of war, including the Geneva Conventions, in its offensive in Chechnya. ``The indiscriminate use of force and the impact of escalation on innocent civilians is a matter of deep concern to us,'' US State Department spokesman James Rubin said. Attackhelicopters fired missiles at Chechnya's second city Gudermes, killing 20 ``bandits,'' according to military news agency AVN, the day after armored reinforcements reportedly arrived to back up forces poised to storm the city. And Russian forces fired four missiles towards Chechnya from their military base near Vladikavkaz in the neighboring republic of North Ossetia. Last month Russian surface missiles fired on the separatist Caucasus republic hit the capital Grozny last month, killing dozens of people. The target of Tuesday's missile attack was not immediately known.An AFP correspondent reported Tuesday that Russian artillery strikes had killed four people overnight in the village of Alkhan-Yurt. Chechen officials said bombing in Grozny had killed one person.In the first signs of unease within Russia at the conflict, the liberal Yabloko party urged Moscow to open peace talks with Grozny, although demanding that the Chechens first hand over its ``terrorists''. Russia has justified invading Chechnya, forthe first time since the disastrous 1994-1996 war which Left the province with de facto independence, to crush ``terrorists''.