The latest attempt happened just one day after North Korea announced that it has detained another U.S. citizen on charges of acting against its sovereignty, making him the fourth American national to be detained by Pyongyang over the past weeks.
In the case of Kim Hak-song, Reuters notes that he had identified as a "Christian missionary planning to start an experimental farm at PUST and was trying to help the North Korean people learn to become self-sufficient".
North Korea said Kim Sang-dok was arrested "for committing criminal acts", but did not elaborate.
The wife of a US citizen who worked at Pyongyang University of Science and Technology (PUST) and was detained from leaving North Korea this weekend pleaded for his immediate release.
Two weeks ago the North arrested Tony Kim, a United States citizen and accounting professor who was lecturing at PUST, accusing him of trying to "overturn" the regime. "North relations right now and we are at a peak", John Delury, associate professor of Chinese studies at Seoul's Yonsei University, told NBC News.
It's a "fair assumption" that North Korea could be detaining US citizens as a diplomatic bargaining chip, Joseph DeTrani, who served as the State Department's special envoy for negotiations with North Korea, told NPR last week.
The four American citizens held in the North also include college student Otto Warmbier and Korean-American pastor Kim Dong-Chul, who received lengthy jail terms for "crimes against the state" and spying, respectively. They were later freed after former U.S. President Bill Clinton visited Pyongyang.
U.S. Secretary of State Rex Tillerson has urged other Asian nations to pressure North Korea to dismantle its programs as well. Cory Gardner has drawn the attention and ire of North Korean leader Kim Jong Un after calling the volatile leader a "whack job" in a TV interview last week.
The administration also claimed that the Central Intelligence Agency bribed a North Korean citizen $40,000 (£32,000) to carry out the assassination.
Is North Korea targeting university for elites? .
Clinton in 2009 flew to Pyongyang to negotiate the release of USA television journalists Laura Ling and Euna Lee, jailed after wandering across to the North from China. He is the second university instructor to be arrested in the past two months.
Washington is concerned about the recent detention of a fourth USA citizen in North Korea and is working with the Swedish Embassy in Pyongyang to resolve the issue, White House Spokesperson Sean Spicer said at a regular press briefing in the US capital on Monday.
In a vague text message to journalists Tuesday, South Korea's Ministry of Foreign Affairs said the report from the Japan Times was "known to either be a matter that the USA could not confirm, or not true".
The North Korean reports also said a "Korean-style anti-terrorist attack" would begin immediately.
Bennett noted that such training has been included and expanded upon in annual wargames hosted by South Korea, which were bigger than ever this year.