A Japanese probe to Venus failed to reach orbit Wednesday and was captured by the sun's gravitational pull in a setback to Japan's shoestring space program, which will have to wait another six years to try again.

The failure in the crucial orbital insertion stage of the probe was a big letdown for Japan, which has never succeeded in an interplanetary mission but has marked some major successes in space on a relatively tight budget that is focused primarily on small-scale science projects.

The top U.S. military officer on Wednesday warned North Korea that the U.S. commitment to helping South Korea defend itself is "unquestioned," even as he pressed China to use its influence to push its ally Pyongyang to change.

Navy Adm. Mike Mullen, the U.S. chairman of the Joint Chiefs of Staff, called recent North Korean aggression, including an artillery attack last month that killed four South Koreans, "belligerent, reckless behavior." He said China appeared unwilling to use its enormous leverage to rein in the North.