South Korean warplanes fired hundreds of warning shots at a Russian military aircraft that entered South Korean airspace Tuesday, defense officials said, in an incident that also involved Japan and China and could complicate relations in an already tense region.

While Russia denied violating any airspace and accused South Korean pilots of being reckless, the Defense Ministry in Seoul said the incident was the first time a Russian military aircraft had violated South Korean airspace.

Two Russian Tu-95 bombers and two Chinese H-6 bombers entered the Korea Air Defense Identification Zone (KADIZ) together early Tuesday, according to the South Korean Defense Ministry.