Russian President Vladimir Putin. (Pool photo via Reuters)

Citing “unfriendly actions” by the United States, the Kremlin announced Monday that Russia would suspend a landmark agreement to dispose of surplus weapons-grade plutonium, yet another sign of deteriorating relations between the two countries.

In a decree released by the Kremlin, President Vladi­mir Putin said Moscow would consider a resumption of the accord only if Washington agreed to several sweeping conditions. Among them: reducing the American military presence in NATO countries near Russia’s border, canceling all sanctions against Russia and compensating Moscow for losses resulting from those sanctions.

The largely symbolic move reversed an agreement once hailed as an example of successful U.S.-Russian cooperation, and comes at a low point in post-Cold War relations between Moscow and Washington. The State Department on Monday said it would suspend bilateral contacts with Russia over Syria, a week after Secretary of State John F. Kerry said the United States might do so because of Russia’s aerial assault on the Syrian city of Aleppo.

Putin’s statement said Moscow took the action because of “the emergence of a threat to strategic stability and as a result of unfriendly actions by the United States of America towards the Russian Federation.” It also cited an “inability of the United States to ensure the implementation of its obligations to utilize surplus weapons-grade plutonium.”

State Department spokeswoman Elizabeth Trudeau gives a statement on the U. S. suspending plans for coordinating counterterrorism strikes in Syria with Russia and negotiations over a cease-fire. (U.S. Department of State)

The list of conditions for restarting the nuclear accord included items that have vexed Moscow for years: The 2012 Magnitsky Act, which punishes Russians seen by Washington as violators of human rights; the 2014 sanctions against Russia introduced after Putin’s annexation of Crimea; and the deployment of NATO forces in the Baltics and former Warsaw Pact countries that joined the alliance after 2000.

Commenting on Putin’s move, the Russian Foreign Ministry said Monday that the United States has “done all it could to destroy the atmosphere encouraging cooperation.”

The ultimatums prompted an angry reaction from Eliot Engel, the top Democrat on the House Foreign Affairs committee.

“If President Putin thinks he can bully the United States, he’s sorely mistaken,” said Engel, of New York. “Once again, we are reminded that American sanctions are having a significant impact on Russia’s economy and that Mr. Putin can’t resist threatening others and acting against his country’s own best interests.”

Ed Royce, of California, the top Republican on the committee, blamed President Obama: “Years of empty words from this administration, from Syria to Ukraine, seem to have convinced Putin he can get away with anything.”

The suspended nuclear accord, signed in 2000 and updated in 2010, required both countries to dispose of 34 tons of weapons-grade plutonium, enough to make approximately 17,000 nuclear weapons, according to a State Department document released after the 2010 signing.

Russia had already soured on the deal over differences with the United States on how to dispose of the plutonium. Moscow says it has already opened a plant that converts the weapons grade material into fuel know as MOX, which can be used in commercial reactors; construction of a similar U.S. plant in South Carolina has been plagued by delays and cost overruns.

The U.S. side has been split between those who want to build a plant as a way to encourage the Russians, and those who believe it safer and cheaper to dilute the plutonium into less harmful material and dispose of it, said George Perkovich, vice president for studies at the Carnegie Endowment for International Peace.

Putin’s move, Perkovich said, “is not a shock,” and reflects more of an opportunity for Moscow “to register political dissatisfaction” than a serious threat to nuclear non-proliferation, and is not as serious as concerns about the nuclear programs in North Korea, Iran, and Pakistan and India. Worries about the security of Russia’s nuclear materials, which approached crisis proportions in the years following the breakup of the Soviet Union, have abated, Perkovich said.

“The concern of somebody just walking off with plutonium has decreased,” he said.

Opponents of the South Carolina plant saw Russia’s decision to suspend as cause to permanently halt construction.

“Russia’s announcement today that it is suspending the U.S.-Russian plutonium disposition agreement removes the last rationale for support of the U.S. MOX program as a means to dispose of excess U.S. plutonium,” Edwin Lyman, senior scientist at the Union of Concerned Scientists, said in a statement. “Not another taxpayer dollar should be wasted on this project.”

Karoun Demirjian contributed to this report.