Putin replied and warned to be "very, very careful".
Rising tensions
In recent days, Donald Trump has been at the center of rising tensions with Russia, after deciding to move two nuclear submarines close to Russia in response to remarks by former president Dmitry Medvedev, which Trump called "highly provocative statements".
The risk
Medvedev, now deputy chairman of the Security Council under Vladimir Putin, warned of the risk of nuclear conflict if the United States stepped up its military aid to Ukraine.
His arsenal
He asserted that Russia would not hesitate to use its arsenal in the event of a serious threat, mentioned the "Dead Hand" automatic retaliation system, and felt that each new escalation brought the United States closer to a confrontation with Moscow.
An act of power
Trump responded by deploying two US nuclear submarines near Russia, presenting the move as an act of power and deterrence.
"Very, very careful"
A spokesman for Vladimir Putin called on Trump to show restraint in his nuclear rhetoric, saying: "We urge everyone to be very, very careful in their statements, especially when it comes to such a sensitive topic as nuclear rhetoric." He also put the deployment of American submarines into perspective, describing it as simply a regular patrol, as is customary in this type of operation.