North Korea's latest missile launches did not violate a pledge its leader Kim Jong Un made to US President Donald Trump, a senior US official said on Thursday, but efforts to resume denuclearisation talks remained in doubt.
North Korean state television showed rockets launching from a vehicle that had been blurred in photos to obscure its features.
The launch came six days after North Korea tested two short-range ballistic missiles, its first tests since Kim and Trump met on June 30 and agreed to revive stalled denuclearisation talks.
The latest launches appeared intended to put pressure on South Korea and the United States to stop planned military exercises, analysts said and came as diplomats criss-cross the region this week in the hope of restarting the talks.
"But you have to ask when the real diplomacy is going to begin when the working-level discussions on denuclearisation will begin," he said.
Watch: North Korea fires two short-range ballistic missiles
North Korea's tests of short-range missiles over the past week happened despite the meeting between Kim and Trump on June 30 at demilitarised zone (DMZ) between the two Koreas at which they agreed to revive their talks on North Korea's weapons.
South Korea's intelligence agency told lawmakers more North Korean missile tests were possible this month, said Lee Eun-jae, one of the lawmakers.
Massachusetts Institute of Technology professor Vipin Narang said the missile tests were part of the North Korean leader's approach to diplomacy, "He's saying it will take more than a photo-op to get things moving."
The tests were a stark reminder that every day the United States and its allies failed to secure an agreement is a day that North Korea continues to improve and expand its nuclear and missile arsenals, he said.
US officials have played down the tests.
On Thursday, Secretary of State Mike Pompeo said he hoped talks would start soon, though he "regretted" that a highly anticipated meeting with North Korean Foreign Minister Ri Yong Ho would not take place in Thailand this week.
Ri has cancelled a trip to an Association of Southeast Asian Nations (ASEAN) conference in Bangkok that Pompeo is attending.
"We stand ready to continue our diplomatic conversation with North Korea," Pompeo told a news conference with his Thai counterpart, adding he was optimistic Kim would deploy his team for working-level talks "before too long".
A summit between Trump and Kim in Vietnam in February collapsed after they failed to reconcile differences between US demands for North Korea's complete denuclearisation and North Korean demands for sanctions relief.
The North Korean photographs of the missile test appeared to show a type of multiple-launch rocket system (MLRS). Such systems form a major part of North Korea's conventional arsenal, according to a 2018 assessment by the South's defence ministry.
The North Korean military has nearly 5,500 MLRS, along with 8,600 field guns, 4,300 tanks, and 2,500 armoured vehicles, the ministry said.
Wednesday's test verified the combat effectiveness of the overall rocket system and Kim predicted "it would be inescapable distress to the forces becoming a fat target of the weapon", KCNA said.
It said the rocket system would play a major role in ground military operations. Such operations would most likely be directed at South Korea.
South Korea's Joint Chiefs of Staff said the North had fired ballistic missiles that flew about 250 km (155 miles).
The missiles launched last week were a different type of short-range ballistic missile, which experts said were designed to make interception difficult.
Ballistic missiles would violate UN resolutions designed to press North Korea to give up its nuclear weapons and missile programmes.
Britain, Germany and France have asked the UN Security Council to meet on Thursday to discuss the missile launches, diplomats said.
UN Secretary-General Antonio Guterres believed the launches were "just another reminder of the importance of restarting talks on the denuclearisation of the Korean peninsula", UN spokesman Stephane Dujarric told reporters.
The South Korean military also said a North Korean soldier had crossed the DMZ on Wednesday and asked to defect to the South.
South Korean nuclear envoy Lee Do-hoon met US Special Representative for North Korea Stephen Biegun on Wednesday on the sidelines of the ASEAN conference in Bangkok.
South Korea's foreign ministry said they discussed the missile tests and vowed diplomatic efforts for an early restart of working-level talks.
China welcomed the US readiness to restart the working-level talks, top Chinese diplomat Wang Yi said in Bangkok, following talks with Pompeo.
The United States does not plan to make changes to this month's military drill with South Korea, a senior US defence official said, despite the missile tests.
"We have to do two things, we have to give the diplomats appropriate space for their diplomacy and help create an environment that is conducive to the talks when they resume ... and we have to maintain readiness," the US official said.
Kim oversaw the first test-firing of a 'new-type large-calibre multiple-launch guided rocket system' on Wednesday, North Korean state media reported.