SEOUL, South Korea (AP) — North Korea fired six short-range projectiles into the sea off its east coast Thursday, Seoul officials said, just hours after the U.N. Security Council approved the toughest sanctions on Pyongyang in two decades for its recent nuclear test and long-range rocket launch.

The North's launches also come shortly after Seoul's parliament passed its first legislation on human rights in North Korea.

Defense spokesman Moon Sang Gyun said the projectiles were fired from the eastern coastal town of Wonsan, adding authorities were trying to determine what exactly North Korea fired. The projectiles could be missiles, artillery or rockets, according to the Defense Ministry.

A South Korean official from the Joint Chiefs of Staff, who did not want to be named, citing office rules, said that North Korea fired six projectiles that flew about 100 to 150 kilometers (60 to 90 miles) before landing in the sea.

North Korea routinely test-fires missiles and rockets, but it often conducts more weapons launches when angered at international condemnation.

Thursday's launch was seen as a "low-level" response to the U.N. sanctions, with Pyongyang unlikely to launch any major provocation until a landmark ruling Workers' Party convention in May, according to Yang Moo-jin, a professor at the University of North Korean Studies in Seoul.

The U.S. State Department said it had seen reports of the launches and was monitoring the situation.

Pyongyang conducted its fourth nuclear test in January, making the widely disputed claim that it successfully detonated a hydrogen bomb. Last month, it put a satellite into orbit on a long-range rocket that the United Nations and others see as a cover for a test of banned ballistic missile technology.

The new U.N. sanctions include mandatory inspections of cargo leaving and entering North Korea by land, sea or air; a ban on all sales or transfers of small arms and light weapons to Pyongyang; and expulsion of diplomats from the North who engage in "illicit activities."

South Korea's National Assembly passed the human rights bill shortly before the U.N. sanctions were unanimously approved. The Cabinet Council endorsed the bill on Thursday. It will become law after it is signed by President Park Geun-hye.

North Korea has warned that enactment of the law would result in "miserable ruin." It views any criticism of its rights situation as part of a U.S.-led plot to overthrow its government, a reason why it says it needs nuclear weapons.

The bill would establish a center in South Korea's Unification Ministry tasked with collecting, archiving and publishing information about human rights in North Korea. It is required to transfer that information to the Justice Ministry, a step parliamentary officials say would provide legal grounds to punish rights violators in North Korea when the two Koreas eventually reunify.

In 2014, a U.N. commission of inquiry on North Korea published a report laying out abuses such as a harsh system of political prison camps holding up to 120,000 people. The commission urged the Security Council to refer North Korea to the International Criminal Court over its human rights record.

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Associated Press writer Kim Tong-hyung contributed to this report.