The New York Times says military analysts are increasingly concerned about North Korea's advanced, underestimated and highly lethal biological weapons. 

Quoting analysis by the Middlebury Institute of International Studies at Monterey, the U.S. daily reported on Tuesday that North Korea is collaborating with foreign researchers to learn biotechnology skills and build machinery and the country’s capabilities are increasing rapidly

According to the analysis, at least 100 research publications that were jointly written by North Korean and foreign scientists have implications for military purposes, such as developing weapons of mass destruction. The daily said the collaborations may violate international sanctions. 

The report also quoted experts as saying that satellite images and internet scrutiny of the North suggest that Pyongyang is newly interested in biotechnology and germ advances.