 BBC News with Chris Barrow. At their summit in Washington, NATO leaders have said they'll support Ukraine's irreversible path to membership of the alliance. They've also promised billions more dollars in military aid, as well as logistical support and training for Ukrainian troops. For the first time, a US senator has joined the growing number of Democratic politicians calling for Joe Biden to step down from the presidential race. Peter Welch said Mr Biden should withdraw for the good of the country.