Seoul: North Korea test-fired a ballistic missile, on Sunday, the latest in a series of launches that have sparked international condemnation and threats of tougher United Nations (UN) sanctions.

The South’s military said it could not yet identify the type of missile fired from Pukchang in South Pyongan province but it travelled about 500km. Washington described it as a medium-range missile.

“Our military is closely monitoring signs for additional provocation by the North Korean military and we are keeping a full military readiness,” said a statement from the South’s Joint Chiefs of Staff.

The launch came just one week after the North fired a Hwasong-12 intermediate-range missile, which according to Pyongyang flew almost 800km and could carry a “heavy” nuclear warhead. Analysts said the Hwasong travelled further than any previous ballistic missile launched by the North.

The May 14 launch was seen as a significant step forward in the North’s weapons capabilities as it accelerates efforts to develop an intercontinental ballistic missile (ICBM) capable of delivering a nuclear warhead to the continental United States.

The launches, and a threatened sixth nuclear test, have fuelled tension with the administration of US President Donald Trump, who has vowed that such an ICBM launch “won’t happen”.

South Korea’s new President Moon Jae-in called a National Security Council meeting in response to the latest launch, Yonhap news agency reported.

A White House official visiting Saudi Arabia with Trump confirmed the North had test-fired a medium-range ballistic missile but appeared to play down Sunday’s launch.

“We are aware that North Korea launched an MRBM. This system, last tested in February, has a shorter range than the missiles launched in North Korea’s three most recent tests,” the official said on condition of anonymity.

Pyongyang has long had missiles that can reach targets across South Korea and Japan.

With an imputed range of 4,500 kilometres, the Hwasong-12 also puts US bases on the Pacific island of Guam within reach.

The UN Security Council met behind closed doors last Tuesday to discuss tightening sanctions on North Korea after its May 14 launch.

US Ambassador Nikki Haley said the United States was working with China, Pyongyang’s main ally, on a new sanctions resolution and warned that all countries must step up action against North Korea or face measures themselves.

“We all have to send a sign to North Korea, and that is: ‘No more. This is not playtime. This is serious. These threats are not welcome’,” Haley told reporters ahead of the meeting.

“If you are a country that is supplying or supporting North Korea, we will call you out on it,” Haley said.

The North says it needs missiles and nuclear weapons to deter any attack by the United States.

State newspaper Minju Joson on Sunday threatened more launches.

“If the US persists in confrontation with the DPRK [North Korea], the latter will show how the crime-woven history of the US is put to an end,” it said.

“Many more ‘Juche weapons’ capable of striking the US will be launched from this land. This is the DPRK’s answer to the Trump administration,” it said, referring to the national philosophy of “Juche” or self-reliance.