North Korea's "provocative" missile tests have been condemned by the UK and the EU, with Foreign Secretary Boris Johnson warning Pyongyang's actions threaten world peace.
The European Union has also said it would consult with Japan and international partners on how to react.
Four banned ballistic missiles were launched 620 miles, with three of them landing in waters which Japan claims as its exclusive economic zone.
Mr Johnson said the UK was consulting other world powers, including in the UN Security Council, about the latest missile launches.
The test launches appear to be a reaction to huge US-South Korean military drills which those countries consider routine, but are viewed as an invasion rehearsal by Kim Jong Un's Pyongyang regime.
Mr Johnson said: "The UK firmly condemns North Korea's latest ballistic missile launches. These are in violation of multiple UN Security Council resolutions.
"We are working with international partners, including in the UN Security Council, of which the UK currently holds the presidency.
"We urge North Korea to stop its provocative actions, which threaten international peace and security.
"North Korea should instead re-engage with the international community, and take credible, concrete steps to prioritise the well-being of its own people instead of the illegal pursuit of its nuclear and ballistic missile programmes."
Mr Johnson's statement is the latest sign of official concern about the secretive state's missile programme.
EU foreign affairs chief Federica Mogherini said launches were "in utter disregard" of several U.N. resolutions and further raised tension in the region.
She says North Korea needs to return to a dialogue with the international community and immediately halt plans for more such missile launches.
After a ballistic missile test in February, North Korea's ambassador was summoned to the Foreign Office and warned about the country's actions.
Ambassador Choe Il was told to convey the message to the government in Pyongyang in "the strongest possible terms" following the February 11 launch.
AP also contributed to this report