People walk by a TV news program showing an image published Sunday in North Korea's Rodong Sinmun newspaper of North Korea's ballistic missile that the North claimed to have launched from underwater, at Seoul Railway station in Seoul, South Korea, Sunday, April 24, 2016. North Korea said Sunday that it successfully test-fired a ballistic missile from a submarine and warned of its growing ability to cut down its enemies with a "dagger of destruction." South Korea couldn't immediately confirm the claim of success in what marks Pyongyang's latest effort to expand its military might in face of pressure by its neighbors and Washington. The letters on the screen read: "North Korea said it successfully test-fired a ballistic missile." (AP Photo/Ahn Young-joon)
People walk by a TV news program showing an image published Sunday in North Korea's Rodong Sinmun newspaper of North Korea's ballistic missile that the North claimed to have launched from underwater, at Seoul Railway station in Seoul, South Korea, Sunday, April 24, 2016. North Korea said Sunday that it successfully test-fired a ballistic missile from a submarine and warned of its growing ability to cut down its enemies with a "dagger of destruction." South Korea couldn't immediately confirm the claim of success in what marks Pyongyang's latest effort to expand its military might in face of pressure by its neighbors and Washington. The letters on the screen read: "North Korea said it successfully test-fired a ballistic missile." (AP Photo/Ahn Young-joon) Credit: ap — Ahn Young-joon

President Obama said the U.S. won’t back down from strengthening its military alliances and defenses against North Korea until the country “shows seriousness” toward eliminating nuclear weapons from the Korean peninsula.

“If North Korea shows seriousness in denuclearizing the Korean peninsula, then we will be ready to engage in serious conversations with them to reduce tensions,” Obama said Sunday at a news conference with German Chancellor Angela Merkel in Hannover, Germany, the final stop of a three-nation international tour.

North Korea would “have to do better” than announcing “via press release” that it intends to step back from nuclear weapons development, he said.

North Korea on Saturday test-fired a ballistic missile from a submarine, according to the U.S. Strategic Command.

It wasn’t clear how far the missile flew, and the U.S. said it “did not pose a threat to North America.”

The move was the latest in a string of military provocations from the regime of Kim Jong Un, and would represent a significant advance in North Korean weapons capability.

“Although more often than not they fail in many of these tests, they gain knowledge each time they engage in these tests,” Obama said. “We take it very seriously, and so do our allies and so does the entire world.”

In recent months, North Korea has also claimed to have successfully tested its first hydrogen bomb, launched a satellite into orbit, and developed miniaturized nuclear bombs.

North Korea’s foreign minister told the Associated Press on Sunday the country was willing to halt its nuclear tests if the U.S. suspended its annual joint military exercises with South Korea.

Foreign Minister Ri Su Yong also said in the interview that international sanctions wouldn’t change the behavior of the regime.

“If we continue on this path of confrontation, this will lead to very catastrophic results, not only for the two countries but for the whole entire world as well,” he said. “It is really crucial for the United States government to withdraw its hostile policy against the DPRK and as an expression of this stop the military exercises, war exercises, in the Korean Peninsula. Then we will respond likewise.”

The U.S. and South Korea intensified the military exercises, which are expected to continue through the month, after North Korea conducted its fourth nuclear test in January. Approximately 300,000 South Korea troops and 17,000 U.S. troops are participating in the drills, according to the joint U.S. and South Korean military command.

The United Nations also implemented additional sanctions limiting the banking activities of the regime abroad. The U.S. has credited China, which has more financial ties with North Korea, with helping to pass and implement the new penalties.