The United States has deployed a special nuclear "sniffer" aircraft, surveillance drones, and U-2 spy planes to monitor a possible nuclear test by North Korea, a report says.
US officials told NBC News on Thursday that the US Air Force's special sniffer plane, known as a WC-135W Constant Phoenix, is capable of detecting evidence of a nuclear explosion.
The Air Force said in a statement that the aircraft "has been deployed on a routine mission to Northeast Asia. These missions are planned well in advance."
The statement said that the plane carries out about 150 missions in a year at a number of locations across the world, and "is designed to collect accurate information on levels of radiation in the atmosphere in order to monitor compliance with international treaties governing nuclear testing."
North Korea is capable of conducting a nuclear test with little or no warning, according to two American intelligence officials.
"We expect that they are able to do it at any time, without any real warning," one official said. "They have been engaging in steady preparations."
The officials refused to confirm or deny that the United States has detected signs that a nuclear test is imminent.
In a press conference with Italian Prime Minister Paolo Gentiloni on Thursday, US President Donald Trump described North Korea as a "menace," but expressed confidence that Chinese President Xi Jinping would take care of Pyongyang.
"As far as North Korea is concerned, we are in very good shape," said Trump. "I respect [President Xi Jinping] very much, and I think he's working very hard… Some very unusual moves have been made over the past two or three hours and I really have confidence that the president will try very hard."
The remarks came after North Korea conducted a missile launch on Sunday that the US called a failure.
Tensions have increased between North Korea and the US in recent weeks. The US has been unnerved by North Korea’s advancing missile and nuclear programs and has dispatched a military strike group to the Korean Peninsula. Pyongyang has said it is ready for war.
North Korea has threatened the US with “all-out war” and announced that Pyongyang would continue to test missiles on a weekly basis.
Pyongyang believes its missile and nuclear programs act as deterrence against a potential invasion by its adversaries, particularly the US.
The US has military forces in South Korea on a permanent basis, and routinely threatens the North with military action.