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

António Guterres urges two powers to quickly sign new deal as New Start expiresThe 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 t...