North Korea launched a rocket into space on Tuesday believed to be carrying a spy satellite, according to South Korea and Japan.

The hermit kingdom claimed it had successfully launched a satellite into orbit and plans to launch more satellites, South Korean news agency Yonhap reported.

The missile launch on Tuesday evening prompted Japan to issue an emergency warning to its citizens on the island of Okinawa to take cover over a possible threat from North Korea. The alarm has since been lifted.

North Korea is prohibited from conducting satellite launches, according to resolutions imposed by the United Nations Security Council. “Even if the purpose is to launch a satellite, using ballistic missile technology is a violation of a series of U.N. Security Council resolutions,” Japanese Prime Minister Fumio Kishida told reporters on Tuesday. “It is also a matter that greatly affects national security.”

The launch escalates what appears to be a space race between Seoul and Pyongyang after both nations announced plans to launch spy satellites by the end of November. This is North Korea's third attempt at launching the satellite, which it says will be used to monitor the activities of both the U.S. and South Korean military in the region.

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How has South Korea reacted?

On Tuesday night, a statement from South Korea's Joint Chiefs of Staff said it believed Pyongyang had launched "a military reconnaissance satellite" that passed through South Korean airspace. "Our military has heightened its alert posture and is maintaining full readiness, closely sharing information with the United States and Japan concerning North Korea's claimed 'military reconnaissance satellite,'" the statement read.

Seoul had previously issued several warnings to Pyongyang to not go ahead with the launch, indicating that it could suspend the Panmunjom Declaration — a peace agreement signed in 2018 to deescalate tensions at the border — which saw a new era of relative stability on the Korean Peninsula.

Hours before Tuesday's satellite launch, the U.K. government announced a defense agreement with South Korea that would enforce sanctions on North Korea. South Korean President Yoon Suk Yeol traveled to the U.K. on Tuesday for a state visit in which the two nations agreed to foster closer relations. The deal will include holding joint patrols of the South China Sea in a bid to enforce sanctions against North Korea.

When was the last time North Korea tried to launch a satellite?

Pyongyang launched its first satellite in May (the first since 2016) and then again in August, both of which failed. After May’s failed attempt, South Korea retrieved what was left of the satellite from the sea and found the device had no ability for reconnaissance.

Tuesday’s launch is the first since North Korean leader Kim Jong Un traveled to Russia to meet with Russian President Vladimir Putin. During the summit, Putin pledged to help with the building of satellites in a show of a growing partnership.

On Tuesday, North Korea's state-run news agency KCNA stated that the country has a "sovereign right" to "bolster up its defense capabilities" to protect its national security.

"The U.S. and its followers are further pushing ahead with their scheme to round off a satellite monitoring system on the strategic objects of the DPRK and its neighboring countries," the statement said. South Korea plans to launch its own spy satellite, with the help of SpaceX and the United States, next week.