A key international nuclear disarmament treaty has formally collapsed amid mutual recriminations between the west and Russia, and with Nato pledging to boost Europe’s military defences.

The alliance’s secretary general, Jens Stoltenberg, said Nato countries were facing a threat from previously banned Russian land-based cruise missiles that could “reach European cities, with only minutes of warning time”.

The 1987 Intermediate-range Nuclear Forces (INF) treaty, signed by Ronald Reagan and Mikhail Gorbachev, banned all surface-to-surface missiles with a range of between 500km and 5,500km, effectively removing them from Europe.

But the treaty lapsed on Friday after Donald Trump’s administration accused Russia of developing a land-based nuclear-capable cruise missile that the US and its Nato allies say violates the INF range restrictions.

Stoltenberg said the Russian missiles – the 9M729, or by its Nato designation the SSC-8 – were “mobile capable and hard to detect”. As well as being able to strike within Europe, they “lower the threshold for the use of nuclear weapons in armed conflict”.

In response, Russia’s foreign ministry said the deal had been terminated “at the initiative of the US”. Sergei Ryabkov, the deputy foreign minister, urged the US to implement a moratorium on missile deployments.

Stoltenberg said the moratorium proposal was “not a credible offer” because Russia has deployed the disputed missiles for several years, while a string of alliance members joined the Nato leader in blaming Russia.

A 9M729 missile on display during a media briefing in Kubinka, Russia. Photograph: TASS/Barcroft Images

Dominic Raab, the UK foreign secretary, tweeted: “Russia has caused the INF treaty to collapse by secretly developing and deploying a treaty-violating missile system which can target Europe’s capitals. Their contempt for the rules-based international system threatens European security. UK fully supports Nato’s response”.

Poland’s foreign minister also tweeted that Russian actions “gave [the US] no choice”.

Russia, however said that trust between itself and the west over nuclear disarmament was low. “The more Nato says it has no intentions, plans, the less we believe so,” Ryabkov told the Tass news agency.

Stoltenberg said Nato did “not want a new arms race” with Russia but promised that members would work together to agree a “credible deterrent” to what he argued was a renewed threat.

Few precise details were announced but the Nato head said the alliance would focus on enhancing “intelligence, surveillance and reconnaissance; air and missile defences and conventional capabilities”.

Existing nuclear deterrents would have to remain “safe, secure and effective,” Stoltenberg added, although there were no immediate plans to deploy cruise missiles in Europe. Such missiles were once sited at bases such as Greenham Common in the UK.

The US is expected to test ground-launched cruise missiles within weeks, though the House of Representatives, controlled by the Democratic party, is refusing to approve a $96m (£80m) budget for further research and development.

It is not clear that any European country would be willing to allow land-based missiles to be deployed on its soil; one country, Poland, has insisted there would have to be unanimous Nato support for their deployment, which is unlikely.

Jeremy Corbyn, the Labour leader, criticised Trump in a tweet on Friday: “President Trump walking away from the Intermediate-Range Nuclear Forces treaty is yet another destructive decision that makes the world less safe. This reckless act will heighten the threat of a nuclear arms race.”

The Campaign for Nuclear Disarmament (CND) said it had handed in a letter to Downing Street asking Boris Johnson “to guarantee that it will refuse to host intermediate range missiles if it is asked to do so by the US administration”.

Mike Pompeo, the US secretary of state, announced Washington’s formal withdrawal in a prepared statement at a regional forum in Bangkok, minutes after Russia pronounced the treaty to be “dead”.

Both sides had signalled their intention to pull out of the treaty for months, trading accusations of breaking the terms of the deal. “Russia is solely responsible for the treaty’s demise,” Pompeo said in a statement issued at an Association of Southeast Asian Nations (ASEAN) foreign ministers’ meeting.

The INF deal was seen as one of two key arms deals between Russia and the US – the other being the New Start treaty, which keeps the nuclear arsenals of both countries well below their cold war peak.

That deal expires in 2021 and there appears to be little political will from Moscow or Washington to renew it. China has already rebuffed calls from the US to join the New Start treaty.