The US has begun building parts for a new ground-launched cruise missile in anticipation of the end of a cold war treaty that banned them, the Pentagon has confirmed.

The Trump administration declared on 1 February it was no longer bound by the Intermediate-range Nuclear Forces (INF) treaty and would withdraw completely in August, pointing to the deployment of a new Russian missile which the US has complained for more than six years was a violation of the agreement.

Vladimir Putin suspended Russian INF obligations a month later.

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Michelle Baldanza, a Pentagon spokeswoman, said on Monday that fabrication had begun on components for a new ground-launched cruise missile (GLCM), which was first reported by Aviation Week.

It is the first time the US has built such weapons since the 1980s when cruise missiles were deployed in Europe in a tense standoff against Soviet SS-20 missiles.

Baldanza said that in response to Russian violation of the treaty, the US defence department started “treaty-compliant research and development of conventional, ground-launched missile concepts in late 2017”.

She stressed that the missile involved was conventional, not nuclear. She added that because the US had previously observed the INF treaty, the research work was in its early stages, but now that the US was no longer bound by its INF obligations, it was moving forward with development efforts.

She said work had started fabricating “components to support developmental testing of these systems”, adding that this work “would have been inconsistent with our obligations under the treaty”.

“This research and development is designed to be reversible, should Russia return to full and verifiable compliance before we withdraw from the treaty in August 2019,” Baldanza said.

EU warns Trump of nuclear arms race risk after INF withdrawal move Read more

For some years, Russia denied developing a medium-range missile, the 9M729, but after being presented with US intelligence on its existence, argued that its range was just under the lower 500km limit banned under the INF. The argument was not accepted by Washington’s Nato allies, who backed the Trump administration, which blamed Russia for the end of the INF.

Thomas Countryman, former assistant secretary of state for international security and nonproliferation, said it was disappointing that European allies had not put more pressure on Russia on its missile development before Trump pulled out of the INF.

“But it’s not too late for the Europeans to make proposals to suggest a post-INF scenario,” said Countryman, chairman of the board of the Arms Control Association in Washington. He added that an agreement could be made on not deploying Russian and US missiles in Europe, or to pledge not to make any of the new medium-range missiles capable of carrying a nuclear warhead.

Sergey Rogov, director of the institute for the US and Canada at the Russian Academy of Sciences, said that the return of medium-range missiles to Europe would create a much more dangerous situation than the 1980s nuclear standoff.

“If the new US missiles are deployed in the Baltic countries or Poland their flight time to Russia would be three or four minutes,” Rogov said, speaking at the Carnegie International Nuclear Policy Conference in Washington.

He added that would make Russian early warning systems redundant, forcing Russia to rely on carrying out a pre-emptive strike against US weapons, or return to the cold war Perimeter defence system, otherwise known as the “Dead Hand” as it triggered an automatic nuclear response to an attack on Russian command and control systems.

Rogov said he had been assured in October by the US national security adviser, John Bolton, that the US withdrawal from the INF did not signify hostile intent towards Russia but he could not guarantee US missiles would not be deployed close to Russian borders.

“I am struck by the speed of the decision to start work on these missiles,” Rogov said. “And this is happening without legally binding treaties so you are going to have complete chaos.”

Heather Williams, defence studies lecturer at King’s College London, said that the development work did not mean that deployment in Europe was necessarily going to happen.

“But these misperceptions are part of the problem,” Williams said.