‘Grave moment’: end of US-Russia nuclear pact comes at worst possible time, UN chief warns

The New Start pact could not be ending at a worse time, UN secretary general António Guterres says, as ‘the risk of a nuclear weapon being used is the highest in decades’. Photograph: Eduardo Muñoz/Reuters

The UN secretary general, António Guterres, has urged the US and Russia to quickly sign a new nuclear arms control deal, as the existing treaty expired in what he called a “grave moment for international peace and security”.

The last nuclear treaty between the two powers, the New Start agreement, ended on Thursday, formally releasing both Moscow and Washington from a raft of restrictions on their nuclear arsenals and triggering fears of a global arms race.