An American withdrawal, which has been expected for months, would follow years of unresolved dispute over Russian compliance with the pact, known as the Intermediate-Range Nuclear Forces, or INF, treaty. It was the first arms control measure to ban an entire class of weapons: ground-launched cruise missiles with a range between 500 kilometers (310 miles) and 5,000 kilometers (3,100 miles). Russia denies that it has been in violation.

U.S. officials also have expressed worry that China, which is not party to the 1987 treaty, is gaining a significant military advantage in Asia by deploying large numbers of missiles with ranges beyond the treaty’s limit. Leaving the INF treaty would allow the Trump administration to counter the Chinese, but it’s unclear how it would do that.

Secretary of State Mike Pompeo said in early December that Washington would give Moscow 60 days to return to compliance before it gave formal notice of withdrawal, with actual withdrawal taking place six months later. The 60-day deadline expires on Saturday, and the administration is expected to say as early as Friday that efforts to work out a compliance deal have failed and that it would suspend its compliance with the treaty’s terms.

The State Department said Pompeo would make a public statement on Friday morning, but it did not mention the topic.

During remarks made at a news conference in Bucharest, Secretary General Stoltenberg, said there are no signs of getting a compliance deal with Russia.

“So we must prepare for a world without the INF Treaty,” he said.

Technically, a U.S. withdrawal would take effect six months after this week’s notification, leaving a small window for saving the treaty. However, in talks this week in Beijing, the U.S. and Russia reported no breakthrough in their dispute, leaving little reason to think either side would change its stance on whether a Russian cruise missile violates the pact.

A Russian deputy foreign minister, Sergei Ryabkov, was quoted by the Russian state news agency Tass as saying after the Beijing talks Thursday, “Unfortunately, there is no progress. The position of the American side is very tough and like an ultimatum.” He said he expects Washington now to suspend its obligations under the treaty, although he added that Moscow remains ready to “search for solutions” that could keep the treaty in force.

U.S. withdrawal raises the prospect of further deterioration in U.S.-Russian relations, which already are arguably at the lowest point in decades, and debate among U.S. allies in Europe over whether Russia’s alleged violations warrant a countermeasure such as deployment of an equivalent American missile in Europe. The U.S. has no nuclear-capable missiles based in Europe; the last of that type and range were withdrawn in line with the INF treaty.

The prospect of U.S. withdrawal from the INF pact has stirred concern globally. The mayor of Des Moines, Iowa, Frank Cownie, is among dozens of local officials and lawmakers in the U.S., Canada, Europe and elsewhere who signed a letter this week to President Donald Trump and Russian President Vladimir Putin expressing worry at the “unraveling” of the INF treaty and other arms constraints.

“Withdrawing from treaties takes a step in the wrong direction,” Cownie said in a telephone interview. “It’s wasn’t just Des Moines, Iowa. It’s people from all around this country that are concerned about the future of our cities, of our country, of this planet.”

The American ambassador to NATO, Kay Bailey Hutchison, set the rhetorical stage for Washington’s withdrawal announcement by asserting Thursday that Russia has been in violation for years, including in Ukraine. She said in a tweet and a video message about the INF treaty that Russia is to blame for its demise.

“Russia consistently refuses to acknowledge its violation and continues to push disinformation and false narratives regarding its illegal missile,” she said. “When only one party respects an arms control treaty while the other side flaunts it, it leaves one side vulnerable, no one is safer, and (it) discredits the very idea of arms control.”

Nuclear weapons experts at the Carnegie Endowment for International Peace said in a statement this week that while Russia’s violation of the INF treaty is a serious problem, U.S. withdrawal under current circumstances would be counterproductive.

“Leaving the INF treaty will unleash a new missile competition between the United States and Russia,” they said.

Kingston Reif, director for disarmament at the Arms Control Association, said Thursday the Trump administration has failed to exhaust diplomatic options to save the treaty. What’s more, “it has no strategy to prevent Russia from building and fielding even more intermediate-range missiles in the absence of the agreement.”

Reif said the period between now and August, when the U.S. withdrawal would take effect, offers a last chance to save the treaty, but he sees little prospect of that happening. He argues that Trump’s national security adviser, John Bolton, is “unlikely to miss the opportunity to kill an agreement he has long despised.”

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Associated Press writer Lynn Berry contributed to this report.