International Atomic Energy Agency (IAEA) Director General Rafael Grossi is making a four-day trip to South Korea as concerns grow that North Korea is readying another nuclear test.

"The IAEA chief's four-day visit to South Korea this week is an enticing opportunity for North Korea to conduct its much-anticipated seventh nuclear test," Sung-Yoon Lee, a professor at the Fletcher School at Tufts University and Korea expert, told Fox News Digital. "While Mr. Grossi has openly stated that he wishes to visit Pyongyang and meet Kim Jong Un, North Korean leaders have shown a propensity to rub it in, that is, add insult to injury, with each nuclear test, thus strengthening their leverage for the next round of talks."

Lee's comments come as the Korea Times reported Monday that Rossi will travel to South Korea Tuesday at the invitation of South Korean foreign ministry, meeting with Foreign Minister Park Jin to discuss North Korea's continued nuclear development. The two are also expected to discuss Japan's plans to dispose radioactive water from its Fukushima nuclear power plant into the ocean next year, which South Korean officials have expressed concern about.

The meeting comes as concerns have grown that North Korea could be on the cusp of another nuclear weapons test amid reports that Tunnel 3 at the Punggye-ri nuclear test site has been ready for a test since May, the same site of the country's 2018 nuclear test.

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"Tunnel 3 at its nuclear test site has been primed since May. While few, if any, outside North Korea know exactly when the next nuclear test is coming, it’s fair to assume that the timing of it will suggest a major insult or celebration," Lee said. 

Grossi's trip to South Korea will be his first since he took office in December 2019 and the first for an IAEA director general since September 2017, something Lee believes may be seen as an opportunity for North Korean leaders.

"The North’s first nuclear test took place on Oct 10, 2006, over a three-day holiday weekend in the U.S. Its second was on May 25, 2009, Memorial Day in the U.S.," Lee said. "Kim Jong Il, the current Great Leader’s dad, ordered the blast just one hour after issuing a condolence message to the family of former South Korean President Roh Moo Hyun (2003-2008), who had committed suicide two days before while under investigation for corruption. Such an insult despite Roh having furnished Kim with $4.4 billion in cash, food, fertilizer, etc., the most by any South Korean leader."

Lee pointed out that North Korean leaders have also used nuclear tests to "stick it to the Chinese," noting their 2013 test that took place "in the middle of China’s Lunar New Year celebrations, its biggest holiday, which was the first for Xi Jinping as the top leader."

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"The fourth nuclear test was on Jan 6, 2016, four days after the hostage-taking of Otto Warmbier, a U.S. college student from Ohio (and two days shy of Kim Jong Un’s birthday)," Lee said. "The fifth test was on Sept 9 later in the year, the North’s Nation Foundation Day. Its sixth took place on Sept 3, 2017, right before Xi Jinping was to deliver an address at a major multilateral forum in Xiamen, China"

Speaking to South Korean media Monday, Grossi noted the progress on Tunnel 3 and said he did not rule out the possibility a test was imminent, though he argued the planning for such tests typically take more time.

However, he expressed concern at the pace of North Korea's nuclear weapons program, noting that the successful test of the ICBM, Hwasong-17, which can reach the United States.

Lee believes North Korea will time their next test to achieve maximum "psychological effect," which the country would then attempt to use to gain concessions from the international community.

"Pyongyang presumes that sticking it to its interlocutors—even outright insulting them—achieves the psychological effect of rendering them more desperate and even more prone to making concessions when it eventually calls for talks," Lee said.