Zapopan, June 18 -- Ahead of his side's FIFA World Cup match against co-hosts Mexico, South Korea coach Hong Myung-bo described the appearance of a drone during their training session as "unfortunate".

Mexican security forces told Reuters that the drone was intercepted over the training ground on Tuesday, as it was not registered. The intervention was under a security operation implemented across the cities hosting World Cup matches, which involves coordination of thousands of personnel and technology devices.

The heightened measures are because authorities are trying to boost safety in Jalissco, a state which has faced a lot of criminal activity from violent groups fighting over drug trafficking routes and other crimes. The interruptio...