The US military and intelligence services assume that North Korea will restart underground nuclear testing as Kim Jong Un prepares to conduct a missile test before the end of the month.News1-Dong-A Ilbo via Getty Images

According to three US sources, the US military and intelligence services believe North Korea will restart underground nuclear testing this month. The evaluation finds that Kim Jong Un's administration is preparing to conduct a nuclear test at the Punggye-ri nuclear test site before the end of the month.

Satellite photography has revealed signs of people and vehicle movement at the test site, but authorities are unsure if the regime has stored nuclear material in one of the test site's subterranean tunnels, which the US has been closely monitoring. If North Korea conducts an underground nuclear test, it will be the country's eighth and first in over five years. Later this month, US Vice President Joe Biden will go to South Korea and Japan.

US, South Korea, and Japan to Discuss Issues Concerning North Korea

It wouldn't be the first time a nuclear test has hovered over a presidential visit: North Korea was planning for one when former President Barack Obama visited South Korea in 2014, and North Korea conducted one shortly after Obama and other global leaders left Asia after a meeting in 2016.

The White House is unconcerned about the President's trip to East Asia later this month, according to White House press secretary Jen Psaki, according to NCN. As stated by White House press secretary Jen Psaki, North Korea's provocative behavior is likely to be a prominent component of the agenda in conversations between US President Joe Biden and his South Korean counterpart Yoon Suk-yeol during the US-ROK (Republic of Korea) Summit.

The US-ROK Summit will take place on the 20th and 21st of May. The convention will be hosted by South Korean President-elect Yoon Suk-yeol, who takes office on May 10. North Korea's threats of nuclear attack against its rivals are intensifying as the meeting takes place. On Tuesday, Pyongyang launched its 14th suspected ballistic missile into the Sea of Japan since the year began.

North Korean dictator Kim Jong Un has promised to build and improve Pyongyang's nuclear and military capabilities. US Defense Secretary Lloyd Austin used Kim Jong Un's repeated threats to justify a $773 billion increase in the defense budget before the Senate Committee on Tuesday, as per Republic World.

North Korea Slams South's New President

Meanwhile, a prominent North Korean propaganda website criticized South Korea's incoming President Yoon Suk-yeol on Thursday, branding him as pro-US and aggressive. Yoon Suk-yeol has pledged to take a harsher stance on Pyongyang's nuclear tests.

President Yoon Suk-yeol, a conservative slated to assume office on May 10, has yet to receive any remarks from the North's state media, although the website Uriminzokkiri slammed him ahead of his inauguration.

It was in response to MYoon's remarks that he would approve a pre-emptive strike on North Korea if there were indicators of an impending attack, as well as his classification of the neighboring country as a major adversary.

Outgoing progressive President Moon Jae-in, who had attempted to normalize relations, scorned such portrayal of the North. The propaganda site's comments differ from previous practice, in which state media have trumpeted news of a North Korean missile test the next day but have remained mute on Wednesday's weapons test, Straits Times reported.