Washington (CNN) Secretary of State Mike Pompeo announced Friday that the US is suspending the Intermediate-Range Nuclear Forces Treaty, a key pact with Russia that has been a centerpiece of European security since the Cold War.

"For years, Russia has violated the terms of the Intermediate-Range Nuclear Forces Treaty without remorse," Pompeo said, speaking from the State Department. "Russia's violations put millions of Europeans and Americans at greater risk."

"It is our duty to respond appropriately," Pompeo said, adding that the US had provided "ample time" for Russia to return to compliance.

The long-expected suspension, which has raised concerns about a renewed arms race with Moscow and put European allies on edge, goes into effect on Saturday. Pompeo's announcement starts a 180-day clock to complete withdrawal unless Russia returns to compliance with the 1987 agreement.

President Donald Trump and his senior officials had been signaling for months that they were ready to pull out of the INF treaty, which the US accuses Moscow of violating since 2014.

'Full support'

"The United States has fully adhered to the INF Treaty for more than 30 years, but we will not remain constrained by its terms while Russia misrepresents its actions," Trump said in a statement Friday. "We cannot be the only country in the world unilaterally bound by this treaty, or any other."

Later, at the White House, the President hinted to reporters that he'd be open to negotiations on a new treaty but did not mention Russia by name -- the only other signatory to the pact.

"I hope that you're able to get everybody in a big and beautiful room and do a new treaty that would be much better, but certainly I would like to see that," Trump said, according to pool reports. "But you have to have everybody adhere to it and you have a certain side that almost pretends it doesn't exist.'

"So unless we're going to have something we all agree to we can't be put at the disadvantage of going by a treaty, limiting what we do, when somebody else doesn't go by that treaty," Trump said.

While Russia and the US are the only two parties to the treaty, but it significantly affects European security.

The ground-based nuclear tipped cruise missiles covered by the bilateral agreement can fly between 310 to 3,100 miles, making them a threat to Europe, where officials have unanimously backed the US decision, even as they consider their next steps and admit having little to no optimism that the treaty can be saved.

In a statement, NATO said America's allies "fully support" the US decision because of Russia's threat to Euro-Atlantic security and its refusal to provide any credible response or take any steps towards full and verifiable compliance.

NATO urged Russia to use the next six months to "return to full and verifiable compliance to preserve the INF Treaty."

Arms control experts sound the alarm

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"We are heading into a direction we have not been in in 40 years: no arms control limits or rules that we are both following, and that is very dangerous," said Lynn Rusten, a senior director for arms control and nonproliferation at the National Security Council during the Obama administration who is now a vice president at the Nuclear Threat Initiative.

US officials and lawmakers have expressed concern that the treaty is allowing China to gain a military advantage, as Beijing is not bound by the INF treaty's limits on intermediate range missiles that currently constrain the US.

Trump appeared to confirm this in his Friday remarks to reporters, saying, "first of all you have to add countries" to the treaty.

But a senior US administration official denied Beijing is a factor.

"There's a lot of discussion about China," this official said, briefing reporters on the suspension. "It is a reality that China is unconstrained, it is a reality they have more than 1,000 of these weapons, but for the United States this has nothing to do with China. This is solely about Russia's violation of this treaty."

"We simply cannot tolerate this kind of abuse of arms control," the official said.

Russian denials

Russia has consistently denied being in violation of the treaty, and on Thursday, Deputy Foreign Minister Sergey Ryabkov said talks with the US hadn't yielded progress.

"Unfortunately, there is no progress. The US position remains rather tough and ultimatum-like," Ryabkov said, according to Russian state media outlet TASS.

"We told the US side that it is impossible to hold dialogue in the conditions of attempted blackmailing of Russia," he added.

Senior US administration officials countered Thursday by laying out Russia's repeated efforts to get the US to agree to dissolve the treaty and years of American effort to get Russia to comply, including 35 diplomatic engagements ranging from the highest political levels to technical talks.

"We have, unfortunately, very little to show for it," said a US official who briefed reporters on condition of anonymity, stressing that "the onus is on Russia."

"Russia continues to deny its violations ... Russia will have this chance. If they are truly interested in preserving this treaty, this is their final chance," the official continued. "It would be in Russia's best interests to return to full and verifiable compliance."

This official noted the "remarkable unity" among the US and its European allies, but European officials say they're concerned about the treaty dissolving and say they will use the six-month window to urge Russia to comply.

"It is clear to us that Russia has violated this treaty and that's why we need to speak to Russia,'' German Chancellor Angela Merkel said at a press conference in Berlin on Friday, shortly before the US announced its intention to suspend the treaty.

Germany will ''do everything we can'' to use the six-month deadline after the termination to hold further talks with Russia, Merkel said.

'What are we looking at instead?'

European officials discussing the fallout in the coming months point to a possible increase in Russian cyber activities, including its influence campaigns, Russia is likely to use the US withdrawal as an excuse to deploy systems elsewhere and the certainty of finger-pointing, as Moscow works to assign blame.

"Russia will feel more legitimized to continue what it's doing now, but also increasing some of its efforts on missile technology and deploying them," said a European official.

A second European official said that "they will threaten, they will try to divide NATO, they'll do anything but stay quiet." The Russians will likely argue that "this is about the US and the US trying to destabilize the international order," this official said, stressing that Europe has been united in its stance, alongside the US, that Russia has been violating the treaty.

"The bigger picture is what kind of sign you're sending out, what message you're sending," said a third European official. "For us, this treaty was extremely important for our security. What are we looking at instead" if it is scrapped, the official asked.