North Korea has reportedly fired at least two short-range ballistic missiles from its eastern coast, Japanese government sources say.

The projectiles, launched early on Thursday from near Wonsan, flew about 430 kilometres to the east, South Korea’s Joint Chiefs of Staff said.

A Japanese government source told Kyodo news the missiles did not reach Japan’s exclusive economic zone and had no impact on the country’s national security.

The firing of ballistic missiles would cast new doubts on efforts to restart denuclearisation talks after US President Donald Trump and North Korean leader Kim Jong-un had a historic meeting at the Korean demilitarised zone at the end of June.

US President Donald Trump and Kim Jong-un in the DMZ. Photo: Getty

The White House, Pentagon and US State Department did not immediately respond to requests for comment on Thursday.

A senior US administration official said: “We are aware of reports of a short-range projectile launched from North Korea. We have no further comment.”

Mr Trump’s national security adviser John Bolton, who has taken a hard line on North Korea, made no mention of the launches in a tweet on Thursday after a visit to South Korea. He referred only to “productive meetings” with South Korean officials on regional security, and building a stronger alliance.

The US and North Korea have pledged to hold new working-level talks soon, but Pyongyang has since sharply criticised looming joint military drills between US and South Korean troops.

North Korea’s foreign ministry said earlier this month that Washington’s pattern of “unilaterally reneging on its commitments” by holding military exercises with South Korea was leading Pyongyang to reconsider its own commitments to discontinue tests of nuclear weapons and intercontinental ballistic missiles.

In May, North Korea’s weapons testing included short-range missiles as well as smaller rockets. At the time, Mr Kim oversaw the first flight of a previously untested weapon: a relatively small, fast missile that experts said would be easier to hide, launch and manoeuvre in flight.

On Tuesday, state news agency KCNA reported that Mr Kim inspected a large, newly built submarine, accompanied by missile program leaders. It potentially signalled continued development of a submarine-launched ballistic missile program.

Talks between North Korea and the US have stalled after a second summit between Mr Trump and Mr Kim in Vietnam in February broke down.

-AAP