The United States on Sunday charged that President Vladimir Putin is "manufacturing threats" as he placed Russian nuclear deterrence forces on high alert amid the Ukraine crisis.
"This is a pattern that we've seen from President Putin through the course of this conflict, which is manufacturing threats that don't exist in order to justify further aggression," White House press secretary Jen Psaki said on ABC when asked about the announcement from Moscow.
Moreover, criticizing Russia's move to keep a nuclear arsenal on high alert, NATO Secretary-General Jens Stoltenberg called Putin's threats of using nuclear defence systems "dangerous rhetoric."
"This is dangerous rhetoric. This is behaviour which is irresponsible," Stoltenberg said on CNN's "State of the Union."
Moscow has the world's second-largest arsenal of nuclear weapons and a huge cache of ballistic missiles which form the backbone of the country's deterrence forces, making his order cause for further international alarm.
The United States and Europe must "really stand together" in response to Russia's military aggression and "threatening rhetoric", NATO chief said, adding the alliance "does not want war".
Ahead of Stoltenberg's remarks, Putin had ordered that nuclear defence systems in Russia be on higher alert, citing Western threats over Moscow's attack on Ukraine.
(with agency inputs)