SEOUL, South Korea -- North Korea tried but failed to fire an intermediate-range missile, U.S. and South Korean officials said Sunday.
It was the first attempted missile launch since the North conducted its fifth and most powerful nuclear test Sept. 9, prompting a wave of international condemnation and efforts to impose new sanctions against the isolated country.
The missile test also occurred hours before the Nimitz-class aircraft carrier USS Ronald Reagan docked in the southeastern port city of Busan on Sunday for what the Navy called a routine visit, after a week of maritime war games with the South Korean navy.
North Korea watchers have predicted in recent weeks that Pyongyang was preparing for another provocation, with satellite images showing activity at its main nuclear testing facility as well as its Sohae satellite-launching station.
The Pentagon said U.S. Strategic Command systems detected the failed launch of a presumed Musudan missile near the northwestern city of Kusong on Saturday.
Pentagon spokesman Gary Ross strongly condemned the missile test and stressed the U.S. commitment to defending allies South Korea and Japan is "ironclad."
"This provocation only serves to increase the international community's resolve to counter the DPRK's prohibited activities," he said, using the acronym for the North's official name, the Democratic People's Republic of Korea.
"We call on North Korea to refrain from actions that further raise tensions in the region," he added.
South Korea's military said the missile failed immediately after launch, according to the Yonhap news agency. The Joint Chiefs of Staff condemned what it called an "illegal provocation" that violated U.N. Security Council resolutions prohibiting the North from using ballistic missile technology.
North Korea has carried out an unprecedented number of missile tests this year, and experts say it is showing clear technical progress in its nuclear weapons program despite numerous failures.
Only one of the Musudan missiles, which have a range that puts them in reach of U.S. bases in Japan and Guam, is believed to have flown far enough to be considered a success. But experts say the North's scientists learn from each failure.
Pyongyang has conducted five underground nuclear tests since 2006 , including two this year -- one in January and the other on Sept. 9 -- causing tensions to rise on the divided peninsula.
The U.S. and South Korea regularly conduct joint military exercises, which they insist are defensive in nature. North Korea, however, considers them a rehearsal for an invasion. It denounced the participation of the USS Ronald Reagan -- the Navy's only forward-deployed carrier -- in naval exercises this week.
The Navy flew a group of reporters out to the ship 150 to 175 miles southwest of Osan Air Base on Friday to show off the carrier's striking power. Nine fighter jets took off and 15 made landings during a 30-minute demonstration of F/A-18 Super Hornets, E-2C Hawkeyes and the EA-18G Growler.
U.S. officials said the Ronald Reagan's arrival in Busan was a routine port call that would allow the 5,500 crew members to engage with their South Korean counterparts. But Navy commanders stressed they were ready to defend the peninsula.
"We remain dedicated to the security of this nation ... and this region," Rear Adm. Brad Cooper, the commander of Naval Forces Korea, said in remarks after the ship docked.
He said the carrier strike group was there "to send a clear signal of the strength of our alliance and our resolve to protect (South Korea) from unprovoked acts of aggression."