Define ‘loose cannon’ (Peretz attacks ‘old’ Jews who go to ‘gentile soirees’)

Here’s why you should read the Financial Times. Its Israel coverage gets Marty Peretz really worked up in ethnocentric fits. I know, that’s not hard to do. Still. By the way, Peretz is calling Henry Siegman "old." Siegman was born in 1930. Peretz was born in 1938.