North Korea launched multiple ballistic missiles toward its eastern waters Sunday, neighbors said, in a move that came hours before South Korean President Lee Jae Myung departed for talks in China.

South Korea’s Joint Chiefs of Staff said in a statement that it detected several ballistic missile launches from North Korea’s capital region around 7:50 a.m. It said the missiles flew about 900 kilometers (560 miles), and that South Korea and U.S. authorities were analyzing details of the launches.

South Korea’s Defense Ministry said the launches violated U.N. Security Council resolutions that ban any ballistic activities by North Korea. The ministry urged North Korea to cease provocative actions immediately and respond to South Korea’s push to restart talks and restore peace on the Korean Peninsula.

Japan’s Defense Minister Shinjiro Koizumi said at least two missile launches by North Korea had been confirmed. “They are a serious problem, threatening the peace and security of our nation, the region and the world,” Koizumi told reporters.

The U.S. military said on social media that the missile launches did not pose an immediate threat to U.S. personnel or territory, or to allies. It said the United States “remains committed to the defense of the U.S. homeland and our allies in the region.”

The launches also arrived before Lee’s four-day trip, during which his office said he would request China, North Korea’s major ally and biggest trading partner, to take “a constructive role” in efforts to promote peace on the Korean Peninsula. South Korea and the U.S. have long asked China to use its influence on North Korea to persuade it to return to talks or give up its nuclear program.

Later Sunday, South Korea convened an emergency national security council meeting to discuss the missile launches. The council reported details of the launches and unspecified South Korean steps to Lee, according to the presidential office.

North Korea’s missile launches were part of a broader series of weapons demonstrations in recent weeks. Experts said North Korea was aiming to show off or review its achievements in the defense sector ahead of its upcoming ruling party congress, the first of its kind in five years, with observers watching for any indication of a new policy toward the United States and a potential restart of long-stalled talks.

The timing also followed North Korea’s reaction to a U.S. military operation in Venezuela. On Saturday, the operation ousted Venezuelan leader Nicolás Maduro from power and brought him to the United States to face narco-terrorism conspiracy charges. North Korea’s Foreign Ministry slammed the operation, saying it again shows “the rogue and brutal nature of the U.S.” It denounced the U.S. act as “the most serious form of encroachment of sovereignty.”

Leif-Eric Easley, a professor of international studies at Ewha Womans University in Seoul, said Kim Jong Un “may feel vindicated about his efforts to build a nuclear deterrent, as he likely did after Trump’s strikes on Iran.” Easley added: “However, leaders of hostile regimes will probably live with greater paranoia after seeing how quickly Maduro was extracted from his country to stand trial in the United States.”

Separately, the Korean Central News Agency said Kim visited a weapons factory on Saturday to review multipurpose precision guided weapons produced there. KCNA cited Kim as ordering officials to expand the current production capacity by about 2.5 times.

North Korea has not announced when it will hold the congress, but South Korea’s spy service said it will likely occur in January or February.