WASHINGTON _ The strained relationship between the United States and Russia deteriorated further Saturday with new threats over Syria but no sign of relief to widespread fighting there.
A senior Russian official warned of "tectonic" consequences if the United States attacked forces loyal to Syrian President Bashar Assad.
The U.S., clearly frustrated and angry at what it describes as brutal, indiscriminate attacks on civilians by Syria and its Russian allies, warned this past week it would end cooperation with Moscow over Syria if the violence continues.
Washington would end diplomatic negotiations with Russia over Syria and renege an offer to share military intelligence if the attacks don't stop, and would consider "all other options," the State Department said.
So far, that has been an empty threat. Though portrayed as an urgent ultimatum delivered Wednesday, the Obama administration by midday Saturday had not changed course. Secretary of State John F. Kerry has spoken by telephone to his Russian counterpart, Sergey Lavrov, nearly every day since.
Still, Moscow reacted angrily to the threat.
Russian news agencies Saturday quoted foreign ministry spokeswoman Maria Zakharova as warning that U.S. military operations against the Syrian army would trigger "terrible, tectonic consequences" across the Middle East.
A State Department spokesman, John Kirby, earlier warned that failure of Russia to secure a cease-fire in Aleppo and beyond would lead to Russians going home "in body bags."
However, the quagmire that Obama administration officials predicted would suck in Russia when it entered the Syrian conflict a year ago has yet to materialize. While Russia, which insists it is targeting only jihadist groups, has paid for its military involvement, it succeeded in saving the Assad regime from defeat, shifting the battlefield dynamic and reasserting its influence in the region.
Also Saturday, reports from Syria indicated that what rebels called a major offensive was underway, with additional attacks by Russian warplanes on supply routes into Aleppo, while Iranian-backed Syrian government ground forces attacked rebel positions in the divided city.
