"Experts said Monday's raid on the Northern Bank cash center was the biggest robbery since 1987, when thieves made off with about $65 million in cash and other valuables from the Knightsbridge Safe Deposit Center in west London.
The tactics in Belfast - particularly the use of hostage-taking as a way to infiltrate a high-security target - suggested a level of sophistication and experience most commonly found within Northern Ireland's rival outlawed groups, particularly the Irish Republican Army.
"This isn't a gang of Belfast criminals who just got together. It's more than that. This looks like a military operation with obvious connotations," said John O'Connor, a former commander of Scotland Yard's elite detective unit in London."