LONDON (AP) — A former NATO secretary-general says Scottish independence could be "cataclysmic" for the Western military alliance at a dangerous time for the world.

George Robertson, an ex-British defense secretary and a Scot, said splitting up Britain "would rob the West of a serious partner just when solidity and cool nerves are going to be vital."

He told the Brookings Institution in Washington on Monday that "the loudest cheers for the break-up of Britain would be from our adversaries."

Robertson, who led NATO between 1999 and 2004, said plans by pro-independence politicians to remove Britain's nuclear-armed submarines from their base in Scotland would make it hard for Scotland to remain a NATO member.

Scotland's pro-independence Deputy First Minister, Nicola Sturgeon, on Tuesday called the comments "insulting and offensive."

Scotland is holding a referendum on independence Sept. 18.