Washington sees North Korea's pursuit of nuclear weapons and ballistic missiles as a threat to world security and to its Asian allies, Japan and South Korea.
North Korea under new leader Kim has pledged to bolster its nuclear arsenal unless Washington scraps what Pyongyang calls a hostile policy.
The launches Wednesday and in April came from a site on the west coast, in the village of Tongchang-ri, about 35 miles from the Chinese border city of Dandong, across the Yalu River from North Korea. The site is 45 miles from the North's main Yongbyon nuclear complex, and is said to have better roads and facilities than previous sites and to allow a southerly flight path meant to keep the rocket from flying over other countries.
Tensions are high between the rival Koreas. The Korean Peninsula remains technically at war, as the 1950-53 conflict ended in a truce, and 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.
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."
The launch also follows South Korea's recent cancellation, because of technical problems, of an attempt to launch its first satellite from its own territory. Two previous attempts in 2009 and 2010 failed.
International condemnation is likely to follow quickly.
The U.N. Security Council has imposed two rounds of sanctions on North Korea following its nuclear tests, and a 2009 resolution orders the North not to conduct any launch using ballistic missile technology.
The council condemned a failed North Korean launch in April and ordered seizure of assets of three North Korean state companies linked to financing, exporting and procuring weapons and missile technology.
Under Security Council resolutions, nations are also barred from buying or selling weapons with North Korea, a key source of revenue for its authoritarian government.
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 believed to have enough weaponized plutonium for at least half a dozen bombs, according to U.S. experts. In 2010 it 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.
A February deal for the United States to provide 240,000 metric tons of food aid in exchange for a freeze in nuclear and missile activities collapsed after the North's April launch.
North Korea said it chose a safe flight path so debris won't endanger neighboring countries. Government spokesman Osamu Fujimura said Wednesday that no debris hit Japanese territory.