The White House said Monday North Korea is "probably the most serious proliferator" of missiles and related technologies.

White House press secretary Scott McClellan made the remark in answer to a questions over whether a U.S.-led international military exercise, scheduled for next month in waters off Australia, is targeted at the North.

The spokesman told reporters that the exercise was "a cooperative effort with countries all across the world to counter proliferation," adding a comment about the North's global 'proliferator' status.

The envisioned military exercise, named the Proliferation Security Initiative, will be carried out as part of a U.S.-led campaign to stem the spread of weapons of mass destruction.