The United States is sending Ukraine sensors that can detect radiation from a nuclear weapon or dirty bomb and can confirm the identity of the attacker.
In part, the goal is to ensure that if Russia detonates a radioactive weapon on Ukrainian soil, its atomic signature and Moscow’s culpability could be verified.
Since Russia invaded Ukraine 14 months ago, experts have been concerned that Russia’s President Vladimir V. Putin might use nuclear weapons for the first time since the Americans bombed Hiroshima and Nagasaki in 1945.
The preparations, mentioned at a House hearing last month and detailed Wednesday by the National Nuclear Security Administration, a federal agency part of the Department of Energy, appear to be the most concrete evidence to date that Washington is taking stronger measures to prepare for the worst possible outcome of the invasion of Ukraine, the second largest nation in Europe.
The Nuclear Emergency Support Team, or NEST, a covert unit of atomic experts run by the security agency, is working with Ukraine to deploy radiation sensors, trained personnel, monitoring information and warning of a lethal radiation.
In a statement sent to The New York Times in response to a reporter’s question, the agency said the atomic sensor network was being deployed “throughout the region” and would have the ability to “detect the size, location, and effects of any nuclear explosion.
In addition, he said that the sensors would deny Russia the opportunity to use nuclear weapons in Ukraine without claiming them.
In one scenario, Washington could use the information collected by the sensor network to rule out the possibility of making a mistake in identifying the attacker who carried out the nuclear explosion.
