One of the projectiles fired by North Korea early Wednesday appears to have fallen into Japan's exclusive economic zone, the top government spokesman said.
"At around 7:10 am (1010 GMT), two projectiles were launched from the eastern coast of North Korea," Yoshihide Suga told reporters.
"One of them appears to have fallen into waters... inside Japan's exclusive economic zone," the chief cabinet secretary said.
The comments came after South Korea's military said the North on Wednesday fired projectiles toward the sea, a day after Pyongyang signalled a resumption of nuclear talks with the US.
Japanese Prime Minister Shinzo Abe said Tokyo would hold a meeting of the National Security Council to decide how to respond to the firing.
"The launching of ballistic missiles violates UN Security Council resolutions and we strongly protest and strongly condemn it," Abe told reporters.
The launch came a day after the North's Vice Foreign Minister Choe Son Hui said Pyongyang had agreed to hold working-level talks with Washington later this week.
The two sides will have "preliminary contact" on Friday and hold negotiations the following day, Choe said in a statement carried by the official Korean Central News Agency.
US State Department spokeswoman Morgan Ortagus later confirmed the talks, which she said would happen "within the next week".
"It seems North Korea wants to make its negotiating position quite clear before talks even begin," Harry Kazianis of the Center for the National Interest in Washington said after Wednesday's launch.
"Pyongyang seems set to push Washington to back off from past demands of full denuclearisation for what are only promises of sanctions relief," he added.
It is not the first time the North has followed up an offer of talks with a weapons test.
Pyongyang tested what it called a "super-large" rocket launcher last month just hours after Choe released a statement saying that the North was willing to resume working-level talks with Washington.
Negotiations between the two have been deadlocked since a second summit between the North's leader Kim Jong Un and US President Donald Trump in February ended without a deal.
The two agreed to restart dialogue during an impromptu meeting at the Demilitarised Zone dividing the two Koreas in June, but the North's anger at a US refusal to cancel joint military deals with South Korea put the process on hold.
Pyongyang also carried out several weapons tests since the meeting that have been downplayed by Trump, who dismissed them as "small" and insisted his personal ties with Kim remained good.
Relations thawed last month after Trump fired his hawkish national security advisor John Bolton, who Pyongyang had repeatedly denounced as a warmonger.
North Korea's chief negotiator responded positively to Trump's suggestion that the two sides try a "new method" of approaching their discussions.
Trump had criticised Bolton's suggestion of the "Libyan model" for North Korea, a reference to a denuclearisation deal with the African nation's former dictator Moamer Kadhafi -- who was killed after being deposed in 2011.