“It was honestly the hardest thing I’ve ever had to do in terms of pure memorisation,” says Affleck. “I’ve always been able to memorise really well, and I realised it’s because I can remember the ideas, the thoughts, the concepts behind the lines. With Russian, you can’t do that: you have to memorise phonetically.”

For all its determination to create an authentic picture of agents at work in the modern world, however, director Robinson realised, like Clancy before him, that The Sum of All Fears is first and foremost an entertainment machine, and that audiences these days expect a few action set-pieces for their money.

Morgan Freeman plays CIA chief William Cabot

Pre-eminent among these (without giving away too much of the plot) is a bomb attack on the Baltimore Forum during a game between the (fictional) Chicago Rockets and the (equally fictional) Alabama Gators. The game was filmed in the Olympic Stadium in Montreal - where much of the location work was done - with real-life football teams the Montreal Alouettes and the Toronto Argonauts battling in front of thousands of real-life fans.

What was not real life, though, was the explosion that followed, which is supposed to destroy the entire the neighbourhood around the stadium, and which is an action set-piece to equal anything previously seen on screen.

But, like everything else in the movie, the pyrotechnics were not being deployed for their own sake: they were there to underline the fact that, in the modern world, weapons of mass destruction are available to unstable regimes - and unstable individuals - in many parts of the world. And all of them have their own (not always logical) agendas. Which is why the world needs Jack Ryan.

“He’s a very believable hero,” concludes Affleck. “He’s moral; he has a strong sense of ethics and he loves his country. The other thing that was really interesting to me about The Sum of All Fears was Phil Robinson’s take on the material. He’s a very politically involved guy who wasn’t interested in making just another action movie. He was looking to make a smart, suspenseful film that reflected the dangers of the current political climate. And that appealed to me tremendously.”