A malfunctioning missile stopped a Russian jet from shooting down a UK spy plane. Here's what could have happened if it had succeeded.

• A hair-raising encounter saw a Russian jet almost shoot down a British spy plane last year.
• Incidents like this raise fears of NATO's Article 5 being triggered, leading to an all-out war.
• In reality, countries have many alternatives before taking that fateful step, one expert says.

A hair-raising encounter between Russian and British military aircraft, which resurfaced in the news last week, raised the question of near-misses and whether a trigger-happy incident between global rivals could spill over into World War III.