Putin, in his first face-to-face meeting with senior editors of international news agencies since the war in Ukraine began, said the West was wrong to assume Russia would never use nuclear weapons, and said the Kremlin's nuclear doctrine should not be taken lightly. 

When asked about NATO chief Jens Stoltenberg's calls to allow Ukraine to use Western weapons to strike Russian territory, Putin differentiated between different missiles but warned allowing Kyiv to strike Russia with ever more powerful weapons was a serious escalation that was drawing the West towards a war with Russia.

Russia's response, the 71-year-old Kremlin chief said, would be to shoot down the Western missiles, and specifically mentioned US ATACMS, and British and French missile systems.

Putin also said Moscow was considering deploying similar high-technology, long-range missiles close enough to strike the states that allowed Ukraine to strike Russian territory with such missiles. 

"If we see that these countries are being drawn into a war against the Russian Federation, then we reserve the right to act in the same way. In general, this is a path to very serious problems," Putin said. 

Putin did not give specifics of where he was considering delivering such missiles.

President Joe Biden authorized Kyiv to launch some US-supplied weapons at military targets inside Russia. Washington still prohibits Kyiv from striking Russia with ATACMS, which have a range of up to 186 miles (300 km), and other long-range US-supplied weapons.

British Foreign Secretary David Cameron, during a visit to Kyiv on May 3, told Reuters Ukraine had a right to use the weapons provided by Britain to strike targets inside Russia, and it was up to Kyiv whether to do so.

Speaking to journalists for more than three hours at the newly built 81-floor Gazprom tower ahead of the annual St. Petersburg International Economic Forum, Putin touched on subjects subjects from the war in Gaza to the upcoming US election.

"No one in the United States is interested in Ukraine, they are interested in the greatness of the United States, which is fighting not for Ukraine and the Ukrainian people, but for its own greatness."

Putin said Russia did not care who the next US president was but said the US court system was clearly being used in a political battle against Republican nominee Donald Trump.

"They are burning themselves from the inside, their state, their political system ... It is obvious all over the world that the prosecution of Trump, especially in court on charges that were formed on the basis of events that happened years ago, without direct proof, is simply using the judicial system in an internal political struggle," said Putin.

More than two years into the deadliest land war in Europe since World War Two, Putin is increasingly talking of the risk of a global conflict as the West grapples with what to do about the advance of Russian troops in Ukraine. 

When asked about the risk of nuclear war, Putin said Russia's nuclear doctrine allowed the use of such weapons.

"For some reason, the West believes that Russia will never use it," Putin said when asked by Reuters about the risk of nuclear escalation over Ukraine during more than three hours of questioning.

"We have a nuclear doctrine, look what it says. If someone's actions threaten our sovereignty and territorial integrity, we consider it possible for us to use all means at our disposal. This should not be taken lightly, superficially."

Russia's published 2020 nuclear doctrine sets out the conditions under which a Russian president would consider using a nuclear weapon: broadly as a response to an attack using nuclear or other weapons of mass destruction, or to the use of conventional weapons against Russia "when the very existence of the state is put under threat."

Putin casts the conflict in Ukraine as part of an existential battle with a declining and decadent West which he says humiliated Russia after the Berlin Wall fell in 1989 by encroaching on what he considers Moscow's sphere of influence, including Ukraine. 

Putin said the West refused to speak about the causes of the war - which he said started in 2014 after a pro-Russian president was toppled in Ukraine's Maidan Revolution. Putin cast it as a US-backed coup.

The West describes the invasion as an imperial-style land grab and has vowed to help Ukraine defeat Russian forces. 

Ukraine says it will not rest until every last Russian soldier is ejected from the areas of Ukraine they control and which Moscow now considers to be parts of Russia.

Western leaders and Ukraine have played down Russia's warnings about the risk of a broader war involving Russia but have repeatedly warned Putin might attack a member of NATO, the world's most powerful military alliance.

Both Putin and Biden have said that a direct conflict between Russia, the world's biggest nuclear power, and US-led NATO would be a step towards World War Three.

"You should not make Russia out to be the enemy. You're only hurting yourself with this, you know?" Putin said.

"They thought that Russia wanted to attack NATO. Have you gone completely crazy? That is as thick as this table. Who came up with this? It is just complete nonsense, you know? Total rubbish."