SEOUL, South Korea -- North Korea announced Saturday that it would attempt to launch a long-range rocket in mid-December, a defiant move just eight months after a failed April bid was widely condemned as a violation of a UN ban against developing its nuclear and missile programs.

The launch, set for Dec. 10 to 22, is likely to heighten already strained tensions with Washington and Seoul as the United States prepares for Barack Obama's second term as U.S. president and South Korea holds its own presidential election on Dec. 19.

This would be North Korea's second launch attempt under leader Kim Jong Un, who took power following his father Kim Jong Il's death nearly a year ago. The announcement by North Korea's space agency followed speculation overseas about stepped-up activity at North Korea's west coast launch pad captured in satellite imagery.

A spokesman for North Korea's Korean Committee for Space Technology said scientists have "analyzed the mistakes" made in the failed April launch and improved the precision of its Unha rocket and Kwangmyongsong satellite, according to the official Korean Central News Agency.

KCNA said the launch was a request of late leader Kim Jong Il, whose Dec. 17, 2011, death North Koreans are expected to mark with some fanfare. The space agency said the rocket would be mounted with a polar-orbiting Earth observation satellite, and maintained its right to develop a peaceful space program.

Washington considers North Korea's rocket launches to be veiled covers for tests of technology for long-range missiles designed to strike the United States, and such tests are banned by the United Nations.

North Korea has capable short- and medium-range missiles, but long-range launches in 1998, 2006, 2009 and in April of this year ended in failure. North Korea is not known to have succeeded in mounting an atomic bomb on a missile but is believed to have enough weaponized plutonium for at least half a dozen bombs, according to U.S. experts, and in 2010 revealed a uranium enrichment program that could provide a second source of material for nuclear weapons.

Six-nation negotiations on dismantling North Korea's nuclear program in exchange for aid fell apart in early 2009.

In Seoul, South Korean officials have accused North Korea of trying to influence its presidential election with what they consider provocations meant to put pressure on voters and on the United States as the North seeks concessions. Conservative Park Geun-hye, the daughter of late President Park Chung-hee, is facing liberal Moon Jae-in in the South Korean presidential vote. Polls show the candidates in a close race.

Some analysts, however, question whether North Korean scientists have corrected whatever caused the misfire of its last rocket.

"Preparing for a launch less than a year after a failure calls into question whether the North could have analyzed and fixed whatever went wrong," David Wright, a physicist with the Union of Concerned Scientists, wrote on the organization's website this week.

The United States has criticized North Korea's pursuit of nuclear weapons and ballistic missiles as a threat to Asian and world security. In 2009, North Korea conducted rocket and nuclear tests within months of Obama taking office.

"A North Korean 'satellite' launch would be a highly provocative act," State Department spokeswoman Victoria Nuland said in Washington, D.C. "Any North Korean launch using ballistic missile technology is in direct violation of UN Security Council resolutions."

North Korea under its young leader has pledged to bolster its nuclear arsenal unless Washington scraps what the North calls a "hostile" policy. North Korea maintains that it is building bombs to defend itself against what it sees as a U.S. nuclear threat in the region.

This year is the centennial of the birth of national founder Kim Il Sung, the grandfather of Kim Jong Un. According to North Korean propaganda, 2012 is meant to put the North on a path toward a "strong, prosperous and great nation."

"North Korea appears to be under pressure to redeem its April launch failure before the year of the 'strong, prosperous and great nation' ends," said Koh Yu-hwan, a North Korea expert at Dongguk University in Seoul.

He added that a successful rocket launch would raise North Korea's bargaining power with South Korea and the United States "because it means the country is closer to developing missiles capable of carrying nuclear warheads."

Before its last two rocket launches, North Korea notified the International Civil Aviation Organization and the International Maritime Organization about its intentions to launch. IMO spokeswoman Natasha Brown said that as of Friday the organization had not been notified by North Korea.

The North's announcement comes two days after South Korea canceled what would have been the launch of its first satellite from its own territory. Scientists in Seoul cited technical difficulties. South Korea's Foreign Ministry said in a statement that the North's planned launch is "a grave provocation and a head-on challenge to the international community."

North Korea's missile and nuclear programs will be a challenge for Obama in his second term and for the incoming South Korean leader. Washington's most recent attempt to negotiate a freeze of the North's nuclear program and a test moratorium in exchange for food aid collapsed with the April launch.

In Japan, Prime Minister Yoshihiko Noda said he would coordinate with the U.S., South Korea, China and Russia in strongly urging the North to refrain from the rocket launch. Kyodo News agency said Japan also postponed high-level talks with North Korea scheduled for Wednesday and Thursday.

The Korean Peninsula remains in a state of war because the 1950-53 Korean conflict ended in a truce, not a peace treaty. Washington stations nearly 30,000 troops in South Korea as a buttress against any North Korean aggression. Tens of thousands more are in nearby Japan.