It was later confirmed by the US as a short-range ballistic missile, which flew about 450 kilometers before landing in the Sea of Japan, approximately 300 kilometers off the coast of Japan.
South Korea' Joint Chiefs of Staff said that the projectile is "estimated to be a Scud type [missile]," and that the South Korean President "was immediately notified of the situation".
Japanese Chief Cabinet Secretary Yoshihide Suga lodged a protest following the launch, saying that the missile fell in Japan's exclusive economic zone.
Since 2006, Pyongyang has conducted five nuclear tests and a series of missile launches, including launches from submarines.
Many military experts believe that Pyongyang's latest missile launches indicate that North Korea is ready to put a whole family of ballistic missiles into service, capable of hitting a wide array of targets at range.
The ballistic missile which was launched by Pyongyang on Monday was identified as the Scud-B, an analogue of the Soviet-made R-17 Elbrus tactical ballistic missile.
The R-17's range spans between 50 kilometers and 550 kilometers; the yield of its nuclear warhead is from 10 to 550 kilotons.
The missile's guidance system uses three gyroscopes that give it a Circular Error of Probability of 450 meters.
In other words, this is a powerful, but not very accurate weapon which isn't particularly effective during pin-point strikes but which is capable of causing serious damage when used against concentrated ground forces or a city neighborhood, according to experts.
On May 14, North Korea's military launched the Hwangson-12 intercontinental ballistic missile (ICBM), which has a range of up to 5,000 kilometers.
May 21 saw a successful test of the ground-to-ground Pukguksong-2 strategic ballistic missile, which hit a target at a distance of more than 500 kilometers.
"North Korea has said a Pukguksong-2 could carry a nuclear payload. The missile was also fired from a mobile-launch vehicle and used a solid-fuel technology that experts say will make it easier to hide and launch on short notice," the New York Times reported at the time.
Experts do not rule out that the next few weeks will see the launch of the Taepodong-2, which is believed to be North Korea's main ballistic missile, with a range of up to 7,000 kilometers.
It seems that North Korean leader Kim Jong Un is doing his best to speed up the process of introducing the new missiles to his country's arsenal. In this vein, experts say that the tests of three different ballistic missiles in three weeks can be seen as the final stage of this process.
Many experts believe that North Korea currently sees a direct threat emanating from the US and its allies in the Asia-Pacific region, which is why Pyongyang is attempting to create a protective multi-layer nuclear umbrella as soon as possible.
In an interview with Sputnik, Russian military expert Mikhail Khodaryonok specifically pointed to Washington's constant threats of a military solution to the North Korean "missile problem."
"Now time is playing in Kim Jong Un's favor. The more ballistic missiles of different types he has, the more difficult it will be for Washington to achieve something using its military. North Korea is trying to protect itself as soon as possible. From a military and strategic point of view, this is the only way to explain its current behavior," Khodaryonok said.
According to him, "in this whole situation, only the US can be blamed for their constant threats."
"We must say bluntly: as compared with the United States, no other country has taken so many steps to violate the non-proliferation regime," he added.
Deputy Foreign Minister Igor Morgulov, for his part, explained that one of the reasons Pyongyang is ramping up its missile program is that South Korea and Japan intend to join the global missile defense system that the US is consistently developing.
Franz Klintsevich, first deputy chairman of the Russian Upper House's Defense and Security Committee, said in turn that that the only way to reduce tensions in the region is to conclude a peace treaty between North Korea and the United States.
"The conclusion of a peace treaty between Washington and Pyongyang will be the best way out, something which will benefit everyone and which will add to a safe world. By signing this treaty, the Americans will also be able to prove that their actions on the Korean Peninsula are directed neither against Russia nor China. Taking into account the North Korean mentality and the situation inside the country, the first step should be made by the United States," Klintsevich said.
In the meantime, in a telephone conversation on Monday, Japanese Foreign Minister Fumio Kisida and US Secretary of State Rex Tillerson have already agreed to increase pressure on North Korea.
Never miss a story again — sign up to our Telegram channel and we'll keep you up to speed!