SEOUL, South Korea -- South Korea's president says there are signs that North Korea is preparing a fifth nuclear test.
President Park Geun-hye said Monday that North Korea could carry out such a test to try to bolster its internal solidarity amid tough international sanctions imposed over the fourth atomic test and rocket launch conducted earlier this year.
Park didn't elaborate on what signs pointed to another nuclear test, but ordered the military to be ready to deal with any provocation by Pyongyang.
Speculation about a fifth nuclear test increased last month when the North's state media cited leader Kim Jong Un as ordering a test of a nuclear warhead.
Analysts say the atomic test could happen before the country holds a landmark ruling Communist Party congress in Pyongyang in early May.
On Friday, South Korea's Defense Ministry said that a North Korean launch of a missile appearred to have failed.
CBS News' David Martin reported that the missile failed at the launch point and didn't make it to the Sea of Japan.
The ministry on Friday did not immediately give any other details of the launch, which comes as the two Koreas trade threats amid Pyongyang's anger over annual South Korean-U.S. military drills that North Korea calls a rehearsal for an invasion.
The North has fired a slew of missiles and artillery shells into the sea in an apparent protest against the drills.
Pentagon officials were expecting North Korea to test fire an intermediate-range missile Friday morning, Martin reported.
A senior U.S. defense official said the U.S. Strategic Command systems have detected and tracked what officials assessed as a failed North Korean missile launch.
According to the North American Aerospace Defense Command, the missile launched from North Korea did not pose a threat to North America.
"The men and women of USSTRATCOM, NORAD and U.S. Northern Command, and U.S. Pacific Command remain vigilant in the face of North Korean provocations and are fully committed to working closely with our Republic of Korea and Japanese allies to maintain security," a statement from the U.S. military said.
The missile in question is a Musadan, which is road mobile and has enough range to reach the Aleutians and Guam. It's never been tested before, so this was another step toward being able to threaten the U.S. with a nuclear weapon.