North Korea has test-fired a short range missile towards the Sea of Japan, according to reports from the region.
If confirmed, this would be the third time in a month Pyongyang has fired missiles into waters off its coast.
The news came as US nuclear envoy Christopher Hill confirmed that North Korea now had access to funds that had been frozen in a Macau bank.
Pyongyang's military programme, and its nuclear ambitions, have long alarmed the international community.
On Monday, the UN's nuclear watchdog confirmed that its inspectors would be travelling to North Korea next week to discuss shutting down its main Yongbyon nuclear reactor.
Unnamed officials in both Japan and South Korea were quoted as saying that the North had test-fired a short-range missile into the Sea of Japan, off its east coast.
"It seems to be part of its routine exercises," an intelligence source was quoted by Yonhap news agency as saying.
According to regional monitors, this is the third recent test. The North is thought to have test-fired two short-range missiles off its western coast in early June, and at least one missile off its eastern coast at the end of May.
Although its dialogue partners in talks on denuclearisation played down the seriousness of these earlier tests, the US described them as "not constructive".
North Korea has pledged to shut down its main reactor at Yongbyon
There has been no official reaction to the latest reports of tests.
Earlier, US chief nuclear negotiator Christopher Hill sounded an upbeat note about progress towards disarming North Korea's nuclear capability.
He told reporters on arrival in Tokyo that Pyongyang now had access to funds which had been trapped in a Macau bank for many years.
The issue had been a continual sticking point for progress towards disarmament.
"My understanding is that today, [the money] was deposited in North Korean accounts in Russia," Mr Hill told reporters.
The row over the bank funds had been rumbling on for months, with North Korea insisting it would not make any progress towards shutting its nuclear reactor - which it had agreed to do as part of a February deal - until it had received the money.
International negotiators hope that now Pyongyang has the money, the landmark deal will be back on track - and that, as agreed, North Korea will "shut down and seal" Yongbyon in exchange for international aid.
"I think this is the time when everyone needs to kind of quicken the pace and work very hard" toward disarmament, Mr Hill said.
To this end, international inspectors are planning to travel to North Korea next week to discuss shutting down the reactor.
Reports from Russia indicate that North Korea itself is intending to close Yongbyon in the second half of July.