Moscow wants an explanation after three Swiss fighter jets were seen flying close to a Russian government airliner.
The plane had been passing over Switzerland carrying members of the Russian delegation and journalists headed for Peru to attend and cover the APEC leaders meeting in Lima.
The Swiss Defense Ministry says its fighters flew alongside the Russian plane for seven minutes. Russia has expressed surprise for the move.
The Swiss Military says it was making a "routine check." such checks are conducted around 400 times a year. Russian President Vladimir Putin flew to Lima on a different plane.
