BRUSSELS — Belgium has come up short in its efforts to prevent extremist attacks time and again, experts say — failing to coordinate intelligence, investigate suspects and control its borders. No country has a perfect record, but Belgium’s is especially bad. On Tuesday, suicide bombers linked to the Islamic State group detonated their explosives at Brussels Airport and on a subway train, killing 32 people including three of the attackers and injuring some 270. Raffaello Pantucci, director of international security studies at the Royal United Services Institute in London, called it “depressingly predictable” that a major attack would occur in Brussels. “There is sort of a perfect union,” he said — a combination of homegrown, hardened Muslim radicals willing to act and possessing the tools and opportunity, as well as a government and law enforcement structure that simply isn’t up to the task. Historically, Belgium has often been found wanting when it comes to sharing intelligence among different agencies, applying what’s learned to police work and controlling its external borders, said Michael O’Hanlon, a senior fellow at the Washington-based Brookings Institution think tank. In addition, he said, Brussels often fails to strike the balance that other countries achieve in weighing the desire to investigate suspected criminal activity and the need to act quickly when an immediate threat is identified. “I don’t believe Belgium has done very well with most of the above over the years,” O’Hanlon said.