The U.S. Air Force has deployed a nuke-sniffer aircraft at its base in Okinawa, Japan, according to multiple sources.
The Boeing WC-135 Constant Phoenix, capable of collecting samples from the atmosphere after a nuclear explosion, arrived at Kadena Air Base, Stars and Stripes reported.
The aircraft may be being deployed ahead of a possible sixth nuclear test in North Korea.
Recent satellite images indicate ongoing activity at the Punggye-ri nuclear site, where Pyongyang conducted its fifth nuclear test in September 2016.
Satoru Kuba, an Okinawan who keeps track of military aircraft activity at Kadena Air Base, and a senior Japan self-defense forces official, each confirmed the WC-135 aircraft's arrival.
Dennis Wilder,a former CIA deputy assistant director for East Asia and the Pacific, posits that North Korea could have a long-range intercontinental ballistic missile capable of reaching the US west coast within four years. (Image via The Heritage Foundation: 2016)
The Constant Phoenix jet touched down at the air base in Okinawa on April 7, the Nikkei newspaper reported.
The aircraft was scheduled to arrive earlier, on March 24, but engine problems resulted in its delay.
The WC-135 jet has been deployed before to Japan and has been carrying out missions in the region since October 2006, when North Korea conducted its first nuclear test.
The aircraft previously found radioactive debris consistent with a North Korea nuclear test during previous missions.
North Korea continues to allocate more than 15 percent of its national budget to defense expenditures, according to Pyongyang's Workers' Party newspaper Rodong Sinmun.
"In order to handle the critical situation of the nuclear threat and endless war provocations of the United States and its followers, we will apportion 15.8 percent of all spending to defense expenditures, in order to strengthen the self-defense and pre-emptive capabilities centered around our nuclear armed forces," Pyongyang stated April 12.
But North Korea also revived its foreign affairs committee during a meetings of its Supreme People's Assembly the second week of April, a possible sign Kim Jong Un may be willing to take a step back from escalating tensions with the United States.