The missile tests also come amid North Korea showcasing a new submarine last week which is capable of carrying up to three ballistic missiles.
South Korea says that North Korea fired ballistic missiles that flew about 250 kilometres and that they appeared to be similar to those launched last week.
Dubbed the KN-23, the missiles are designed to evade missile defence systems by being easier to hide, launch, and manoeuvre in flight.
The two KN-23s launched last week were reported as having a “low-altitude gliding and leaping flight” pattern that would make them hard to intercept.
Some analysts said that the range and the altitude of Wednesday’s flights could indicate a test of those capabilities.
Why missile tests?
The answer is not far to seek. North Korea does not want the United States and South Korea to conduct joint military drills planned for August. The country is also upset by South Korea buying F-35 fighter jets from the US.
July 25 missile tests
The missiles launched on July 25 were North Korea's first missile tests since Kim Jong-Un and Donald Trump met on June 30 and agreed to revive stalled denuclearisation talks.
The missile tests are intended to pressure South Korea and the United States to stop upcoming military drills.
South Korea has bought US-manufactured F-35 stealth fighter jets. It took delivery of its first two F-35 jets in March with more slated to arrive this year.
It has agreed to buy a total of 40 of the advanced aircraft, the last to be delivered by 2021.
Destroy US-manufactured weapons!
North Korean state media said on July 11 that Pyongyang must develop and test “special armaments” to destroy the new US-manufactured weapons.
“There is no room for doubt that the delivery of ‘F-35a’, which is also called an ‘invisible lethal weapon’, is aimed at securing military supremacy over the neighbouring countries in the region and especially opening a ‘gate’ to invading the north in time of emergency on the korean peninsula,” read a statement published by North Korean state news agency KCNA.
'No other choice'
North Korea stated that Pyongyang has no other choice but to develop and test the special armaments to completely destroy the lethal weapons reinforced in South Korea.
US playing down launches
US President Donald Trump and his foreign minister Mike Pompeo had played down last week’s launches.
Pompeo has continued to express hope for a diplomatic way forward with North Korea. For his part, Japanese Prime Minister Shinzo Abe said there was no impact from Wednesday’s launch on Japan’s security.
The missile tests came on a day when Pompeo met ASEAN leaders in Thailand's capital Bangkok.
Trump and Kim last met on June 30 in the Demilitarised Zone (DMZ) between the two Koreas.
Breach of promise
Since then, Pyongyang has accused Washington of breaking a promise by planning to hold joint military exercises with South Korea next month and warned those drills could derail talks.
North Korea has also warned of a possible end to its freeze on nuclear and long-range missile tests that has been in place since 2017. Trump has repeatedly upheld this as evidence of the success of his engagement with Kim.
The February summit between Trump and Kim in Vietnam had collapsed after the leaders failed to reconcile differences between Washington’s demands for Pyongyang’s complete denuclearisation and North Korean demands for sanctions relief.