Prime Minister Fumio Kishida expressed wariness Saturday about recent joint Chinese and Russian bomber flights over waters near Japan, warning that his country is facing the toughest and most complex security environment in postwar times.

"Attempts to change the status quo unilaterally around our country are intensifying," Kishida said in a speech at the Air Self-Defense Force's Iruma Air Base in Saitama Prefecture near Tokyo, adding a "swift" deployment of long-range missiles to boost defense is needed.

In the latest occurrence in June, four Chinese and Russian bombers jointly flew above waters near Japan, prompting the ASDF to scramble fighter jets. Japanese fighters also responded to passing bombers in November last year.

Although Japan's airspace has not been violated, the Defense Ministry conveyed its grave concerns to China and Russia via diplomatic channels, seeing the action as a show of force.

Kishida also noted Japan's decision to update its key defense documents last year and acquire "counterstrike" capabilities, or the ability to hit enemy bases should the need arise. The move is a major policy shift under Japan's war-renouncing Constitution.

The prime minister vowed to secure the necessary funding to build up the country's defenses amid security challenges, including North Korea's missile and nuclear threats.