SEOUL, South Korea — North Korea on Sunday defied international warnings and launched a long-range rocket that the United Nations and others call a cover for a banned test of technology for a missile that could strike the U.S. mainland.

The rocket, fired from North Korea’s west coast and tracked by the governments in South Korea and Japan, came about two hours after an eight-day launch window opened Sunday morning. It follows North Korea’s widely disputed claim last month to have tested a hydrogen bomb. Washington, Seoul and their allies will consider it a further provocation and will push for more tough sanctions in the United Nations.

Japan’s NHK broadcaster reported that debris from the launch was believed to have fallen about 155 miles off the southwest coast of the Korean Peninsula into the East China Sea about 14 minutes after the launch.

NHK also showed footage of an object visible in the skies from the southern island of Okinawa that was believed to be the rocket.

South Korean President Park Geun-hye convened an emergency national security council meeting after the launch.

North Korean rocket and nuclear tests are seen as crucial steps toward the North’s ultimate goal of a nuclear armed long-range missile arsenal. North Korea under leader Kim Jong Un has pledged to bolster its nuclear arsenal unless Washington scraps what Pyongyang calls a hostile policy meant to collapse Kim’s government.

The global criticism began almost immediately.

Japanese Prime Minister Shinzo Abe called the North Korean rocket launch and the recent nuclear test violations of U.N. agreements.

“We absolutely cannot allow this,” he told reporters at the prime minister’s residence. “We will take action to totally protect the safety and well-being of our people.”

Kim Jong Un has overseen two of the North’s four nuclear tests and three long-range rocket tests since taking over after the death of his father, dictator Kim Jong Il, in late 2011.

North Korea says its rocket launches are satellite missions, but the U.S., South Korea and others say they are a covert test of ballistic missile technology. The U.N. Security Council prohibits North Korea from nuclear and ballistic missile activity. Experts say that ballistic missiles and rockets in satellite launches share similar bodies, engines and other technology.