Secretary of State Hillary Clinton called on Russia Wednesday to stop arming Syrian President Bashar Assad's military, suggesting Russia was acting against its own interests by continuing to back the embattled regime. She warned the situation in Syria is "spiraling towards civil war."
The secretary and other U.S. officials also unequivocally rejected Russia's accusation earlier in the day that the U.S. is arming the Syrian opposition.
"The United States has provided no military support to the Syrian opposition. None," Clinton said.
But a day after claiming Russia was providing attack helicopters to the Syrian government, Clinton said the U.S. has "repeatedly urged the Russian government to cut these military ties completely and to suspend all further support and deliveries."
The rapid-fire diplomatic battle between the two countries is quickly escalating as the U.S. tries to pressure Russia to pull back on its support for Assad amid worsening violence inside Syria. Both U.N. and French officials are now describing that conflict as civil war.
Russia and the U.S. are effectively accusing each other of contributing to the violence.
Clinton on Tuesday accused Russia of providing attack helicopters to Assad's regime.
On Wednesday, Russian Foreign Minister Sergei Lavrov defended his country's aid, saying Russia is not violating any international law. And, according to an account from Reuters, Lavrov said: "They (the United States) are providing arms and weapons to the Syrian opposition that can be used in fighting against the Damascus government."
The State Department and White House denied the charge.
"We do NOT -- repeat NOT -- provide arms to anyone in Syria," State Department spokesman Mark Toner said in an email to FoxNews.com.
Toner told FoxNews.com that the U.S. has been "crystal clear on this point." He said the U.S. provides $52 million in emergency humanitarian assistance to the Syrian people through various nongovernmental organizations like the Red Cross.
Toner said the U.S. provides some nonlethal assistance, like communications and medical equipment.
White House Press Secretary Jay Carney also said that: "We do not and have not supplied weapons to the Syrian opposition."
Carney did not describe the conflict as civil war, but warned that could be the outcome if circumstances do not change.
"The situation there is deteriorating, it is deteriorating quickly, it is horrific what Assad is doing to his own people -- and that the window of opportunity to bring about and transition to a democratic future for Syria is closing and will close, and if it does, the chance for a broader sectarian civil war in Syria will be enhanced greatly," Carney said.
Clinton, in claiming that Russia was arming Assad, warned Tuesday that the violence in the country could escalate "quite dramatically."
The latest reports out of Syria, according to state TV, say that Assad's forces have cleared out rebels from the Haffa region.
The developments have led some U.S. lawmakers to call on the Obama administration to get tougher on Russia.
Rep. Ileana Ros-Lehtinen, R-Fla., chairwoman of the House Foreign Affairs Committee, said that in light of Russia's alleged help in providing helicopters, "the Obama administration's string of concessions to Moscow must stop." She cited, among other things, Russia being allowed to host international talks over Iran's nuclear program.
"This is a replay of Moscow's providing weapons and assistance to Iran, which have enabled Tehran to repress the Iranian people and threaten its neighbors," she said in a statement regarding the Russian aid to Syria.
Sen. John Cornyn, R-Texas, also has criticized the Pentagon for using a Russian firm to purchase helicopters for the Afghan Army -- even as Russia allegedly sends choppers to the Assad regime.
Cornyn wrote a letter Monday to Defense Secretary Leon Panetta expressing "grave concerns" about U.S. dealings with the firm that is "arming the Assad regime."