Japan's Prime Minister Shinzo Abe says his country will join the United States in taking concrete action against North Korea after its latest ballistic missile test.

On Monday, North Korea test-fired a Scud missile into Japanese waters, the third test in as many weeks and the 12th this year - carried out in defiance of UN sanctions warnings and US threats of possible military action.

"We will never tolerate North Korea's continued provocations that ignore repeated warnings by the international community," Abe told reporters shortly after the test.

"As agreed during the G7 summit, the North Korean problem is the international community's top priority. In order to deter North Korea, we will take concrete action with the United States."

READ MORE: North Korea fires missile in third test in three weeks

Isolated but nuclear-armed, North Korea has test-fired a missile almost every week for the past three weeks.

The latest, a short-range Scud, flew about 450km before landing in the Sea of Japan (East Sea) between the Korean Peninsula and Japan, the US Pacific Command said.

Monday's test also marked the second time this year that a North Korean missile fell close to its neighbour Japan.

Michael Penn, president of the Tokyo-based Shingetsu news agency, told Al Jazeera that the latest test was part of a North Korean effort to strengthen its military against any possible threats from the US.

"The missile technology tests themselves do seem to be the priority of the North Korean regime, to get their technology as strong as possible, as quickly as possible.

"They feel this is their best way forward – to show their own ability to defend themselves against a Trump administration they cannot predict," Penn said.

US: Conflict would be 'catastrophic'

Despite Trump's strident warnings, James Mattis, the US secretary of defence, said in an interview that aired on Sunday before the launch that a war with North Korea would be "catastrophic".

"The North Korean regime has hundreds of artillery cannons and rocket launchers within range of one of the most densely populated cities on Earth, which is the capital of South Korea," he told CBS News.

"This regime is a threat to the region, to Japan, to South Korea. In the event of war, they would bring danger to China and to Russia as well.

READ MORE: North Korea's nuclear weapons - Here is all we know

"But the bottom line is, it would be a catastrophic war if this turns into a combat, if we're not able to resolve this situation through diplomatic means."

Mattis declined to say what kind of action from Pyongyang would constitute a "red line" for Washington, saying the administration needs "political manoeuvre room."

'Direct challenge'

South Korea's new president, Moon Jae-In, ordered a meeting of the national security council to assess the launch, which came a day after North Korea said its leader Kim Jong-un had overseen a test of a new anti-aircraft weapons system.

South Korea condemned the test as a "grave threat" and a challenge to the new leader who advocates dialogue with North Korea in a break from his conservative predecessors.

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"That the North repeated such provocations after the inauguration of our new leadership... is a direct challenge to our demand for peace and denuclearisation of the Korean Peninsula," the foreign ministry said.

The missile launches, and Pyongyang's threat to stage its sixth nuclear test, have prompted calls for tougher UN sanctions and a warning from Trump that military intervention was an option under consideration.