North Korea fired a pair of ballistic missiles towards the sea off the Korean Peninsula’s east coast on Sunday, reported the Associated Press.

The development comes two days after Pyongyang claimed to have performed a key test needed to build a powerful intercontinental ballistic missile designed to strike the United States mainland,

South Korea and Japan said that the two missiles launched on Sunday traveled about 500 kilometers at a maximum altitude of 550 kilometers before landing in the East Sea, also knows as the Sea of Japan.

South Korea’s military said that the missiles were medium-range weapons that were launched at a steep angle, suggesting they could have traveled farther if fired at a standard trajectory.

Top South Korean security officials criticised the firing of the missiles, saying that it took place despite the plight of North Korean “citizens moaning in hunger and cold due to a serious food shortage”.

The officials said South Korea will boost trilateral security cooperation with the US and Japan.

Japanese Vice Defence Minister Toshiro Ino said that the firing of the ballistic missiles “threatens the peace and security of our country, this region, and the international community, absolutely unacceptable,”, reported AFP.

Tensions have increased in the Korean peninsula in recent months as Pyongyang has tested a series of nuclear-capable missiles and also adopted a law allowing the preemptive use of the weapons on a broad number of issues.

In November, North Korea had fired a long-range and two short-range ballistic missiles, forcing Japan and South Korea to issue an emergency alert for their residents.

North Korea has argued its weapons tests are meant to be a warning to the United States and South Korea in the context of their joint military drills that it sees as an invasion rehearsal.

On Thursday, North Korea had tested a “high-thrust solid-fuel motor” for a new strategic weapon, a development that experts say could allow it to possess a more mobile, harder-to-detect arsenal of intercontinental ballistic missiles, according to AP.

A day later, Japan had adopted a national security strategy allowing it to conduct preemptive strikes and fire powerful cruise missiles in order to give itself more offensive footing against threats from China and North Korea.