Russian President Vladimir Putin has said his country will only use its nuclear weapons in response to a nuclear attack on the country.
Putin ruled out any "preemptive nuclear strikes" at an international policy forum in Sochi on October 18, and said Moscow would only use nuclear weapons defensively, if early warning systems spotted nuclear missiles heading toward Russia.
"Our strategy of nuclear-weapons use doesn't envision a preemptive strike. Our concept is a launch under attack," he said.
"Only when we become convinced that there is an incoming attack on the territory of Russia, and that happens within seconds, only after that we would launch a retaliatory strike," he said.
"It would naturally mean a global catastrophe, but I want to emphasize that we can't be those who initiate it because we don't foresee a preventive strike," Putin said. "The aggressor should know that retaliation is inevitable, and he will be destroyed."
"We would be victims of an aggression and would get to heaven as martyrs," Putin said, while those who attacked Russia would "just die and not even have time to repent."
The Russian leader also claimed that new hypersonic missiles his country has developed give it a military edge.
"We have run ahead of the competition. No one has precision hypersonic weapons," he said. "Others are planning to start testing them within the next 1 1/2 to two years, and we already have them on duty."
Russia already has deployed the Kinzhal hypersonic missile. Putin said that another new weapon, the Avangard, is set to enter service in the next few months.
Earlier this year, Putin claimed the Avangard has an intercontinental range and can fly in the atmosphere at a speed 20 times the speed of sound, making it capable of piercing any missile-defense system.
His blunt talk on nuclear weapons comes as Russia's relations with the West remain tense over such issues as the wars in eastern Ukraine and Syria and allegations of Russian meddling in elections.
Putin dismissed U.S. investigations into Russian election interference as an "internal political struggle."
"Some people think that playing the Russian card is a very convenient instrument for solving internal political problems," Putin said. "I hope it will go away. I don't know if it happens after the congressional elections, but it might. Or it may happen after the 2020 U.S. presidential election, when [U.S. President Donald Trump] will no longer have to constantly look back at those who engage in anti-Russian rhetoric."
Putin sharply criticized Washington's issuance of a series of sanctions against Russia, saying such selective economic punishment measures "undermine trust in the dollar as a universal payment instrument and the main reserve currency."
"It's a typical mistake made by an empire," Putin said. "An empire always thinks that it's so powerful that it can afford some mistakes and extra costs. But mistakes and costs multiply, and a moment comes when they become overwhelming in both security and economic spheres."