By Michelle Nichols UNITED NATIONS (Reuters) - The United States called the assault on Aleppo by Syria and Russia "a gift" to Islamic State on Thursday, saying it was sowing doom and would generate more recruits for the militant group. Moscow vowed to press on with its offensive in Syria, while U.S. officials searched for a tougher response to Russia's decision to ignore the peace process and seek a military victory on behalf of Syrian President Bashar al-Assad. United Nations aid chief Stephen O'Brien urged the 15-member U.N. Security Council to stop "tolerating the utter disregard for the most basic provisions of international humanitarian law." The recent focus of the fighting is a Syrian and Russian bid to recapture rebel-held eastern Aleppo.

The Syrian government on Thursday criticized the U.S.-led coalition fighting Islamic State for destroying two bridges on the Euphrates river this week in areas the jihadists hold in the east of the country. Monitoring group the Syrian Observatory for Human Rights said warplanes most probably from the coalition hit the two bridges in Deir al-Zor province on Tuesday and Wednesday, making them unusable. The attacks "confirm the so-called international coalition's intent to bomb and destroy Syrian infrastructure and economic and social establishments through repeated aggressive acts," state TV quoted the foreign ministry as saying.