seoul, south korea - North Korea test-fired three ballistic missiles Wednesday, including what appeared to be an intercontinental ballistic missile, South Korea said, hours after U.S. President Joe Biden wrapped up a visit to Northeast Asia.

U.S. officials had repeatedly warned North Korea could conduct a long-range missile launch, or even a nuclear test, during or around Biden's Asia trip. While North Korea refrained from any tests during Biden's visit, its flurry of launches came just 12 hours after he left Japan.

The first missile, likely an ICBM, flew for about 360 kilometers and reached an altitude of 540 kilometers, South Korea's military said. The North also launched a missile that failed shortly after liftoff, as well as a third ballistic missile that was presumed to be short-range, it added.

In response, South Korea's military says it conducted an exercise involving 30 F-15K fighter jets. The United States and South Korea also conducted a surface-to-surface missile launch, it added.

"Our demonstration of armed forces showed that we are determined to respond to any provocations such as North Korea's ICBM launch and we are capable of precisely striking the origin of the provocation with our military's overwhelming power," South Korea's Joint Chiefs of Staff said in a statement.

The United States and South Korea jointly condemned North Korea's 'destabilizing' ballistic missile tests, according to a White House readout of a phone call between U.S. National Security Advisor Jake Sullivan and his South Korean counterpart, Kim Sung-han. The U.S. also 'reaffirmed the United States' steadfast commitment to the defense' of South Korea.

North Korea has conducted 17 rounds of launches this year. In March, it tested an intercontinental ballistic missile for the first time in nearly five years.

North Korea a focus of Biden's trip

The nuclear-armed North regularly came up during Biden's discussions in South Korea and Japan.

In Seoul, Biden and South Korea's new president, Yoon Suk Yeol, indicated they could soon intensify joint military exercises that had been scaled back since 2018.

In Tokyo, Biden met with the families of Japanese citizens who were kidnapped by North Korean agents decades ago.

At a Tuesday meeting of the Quad - a regional grouping of democracies that includes the United States, Australia, Japan and India - Biden and his counterparts condemned North Korea's "destabilizing ballistic missile development and launches."

North Korea walked away from nuclear talks with the United States in 2019, the same year it resumed ballistic missile tests. Under Biden, the U.S. has repeatedly said it is willing to reenter talks without preconditions.

Biden said in Seoul, however, that he would only meet North Korean leader Kim Jong Un if Kim was "sincere" and "serious" about moving the talks forward.

When asked in Seoul whether he had a message for Kim, Biden replied: "Hello. Period."

Kim has not publicly responded to Biden's greetings. In the past, North Korean officials suggested they would not reenter talks while the United States undertook a "hostile policy" toward the North.

COVID woes

U.S. officials traveling with Biden suggested that North Korea's coronavirus outbreak was one possible reason Pyongyang had not engaged in negotiations.

North Korea had not acknowledged any coronavirus cases until this month, when it reported an explosion of suspected infections. Since May 13, North Korean state media have reported more than 3 million suspected cases.

The outbreak has not prevented North Korea from conducting missile tests. Since it acknowledged the COVID-19 cases, North Korea has fired at least six ballistic missiles.

The North has multiple possible motives for testing weapons, including pressuring the U.S., shoring up domestic political support for leader Kim, ensuring the performance of new weapons and demonstrating deterrence.