Declaring its patience with Russia has run out, the United States on Monday suspended Syria cease-fire talks with Moscow, citing continued military attacks against civilian targets in the war-torn Middle Eastern country.
"This is not a decision that was taken lightly," U.S. State Department spokesman John Kirby said in a statement. Though Washington "spared no effort" in trying to implement the cessation of hostilities, Russia "failed to live up to its own commitments," Kirby said.
"(Russia) was also either unwilling or unable to ensure Syrian regime adherence to which Moscow had agreed," the statement said. "Rather, Russia and the Syrian regime have chosen to pursue a military course."
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Though the talks are suspended, the U.S. will continue to use a channel of communications established with Russia to reduce the possibility of conflicting counterterrorism operations in Syria, the statement said.
Moscow has provided military support to and conducted air strikes in support of the government of Syrian President Bashar al-Assad, while Washington has supported some of the rebel groups fighting to oust the Syrian president.
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The two sides agreed to a cease-fire last month to reduce violence, provide humanitarian access and degrade terrorist groups. But the deal quickly broke down, with each side blaming the other. Subsequent talks failed to resolve the impasse.
“What's clear is that there is nothing more for the U.S. and Russia to talk about with regard to trying to reach an agreement that would reduce the violence inside of Syria,” said White House Press Secretary Josh Earnest. “And that is tragic.”
He added: “Everybody's patience with Russia has run out.”
Moscow says it regrets the U.S. move to suspend the talks. A Russian foreign ministry spokeswoman quoted by local news agencies said Washington is trying to shift blame for not living up to its end of the deal.
U.S. officials had repeatedly threatened to call off the talks unless Russia ended its bombing of the Syrian city of Aleppo. Tensions especially spiked after the September 19 bombing of a United Nations aid convoy, which the U.S. blamed on Russia and Syria.
The U.S. move to pull out of the talks came hours after Russian President Vladimir Putin signed a decree Monday to suspend an agreement with the U.S. on disposing of weapons-grade plutonium, citing Washington's "unfriendly actions."
It also claimed the United States was unable "to ensure the implementation of its obligations to utilize surplus weapons-grade plutonium."
Earnest, the White House spokesman, said the U.S. was disappointed by Russia's decision to unilaterally pull out of the treaty.
The deal, initially signed in 2000 and renewed in 2010, called for both nuclear powers to dispose of weapons-grade plutonium from their defense programs.
Based on the 2010 agreement, signed by Russian Foreign Minister Sergei Lavrov and then U.S. Secretary of State Hillary Clinton, each side would dispose of 34 metric tons of plutonium by burning it in nuclear reactors.
Clinton said that quantity was large enough to make almost 17,000 nuclear weapons.
US-Russia ties plunging
Russia and the United States viewed that deal as a sign of increased cooperation between them toward nuclear nonproliferation.
But ties between Moscow and Washington plunged to the lowest point since the Cold War when Russia annexed Crimea from Ukraine in 2014 and has supported pro-Moscow separatists in eastern Ukraine.
Washington has been instrumental in imposing Western economic sanctions on Russia for its role in the Ukraine crisis.
State Department correspondent Nike Ching and White House Correspondent Mary Alice Salinas contributed to this report