Putin gave an ominous warning about World War III and nuclear competition with the US

Sergei Ilnitsky/Pool via Reuters

• Russian President Vladimir Putin's annual call-in question show contained an ominous warning about World War III.
• Putin quoted Albert Einstein to say that World War III would result in the end of civilization as we know it.
• Putin has the nuclear arsenal to end civilization unilaterally.
• In 2014 he annexed Crimea from Ukraine in a move that resembles the run up to World War II.
• But the US has nuclear weapons of its own, and holds Russia back from being too aggressive or using nukes.

Russian President Vladimir Putin's annual call-in question show contained broad talk of improving Russia's economy, the upcoming soccer World Cup - and some ominous warnings about World War III.

Putin frequently frames his country as resisting Western aggression designed to hold back Russia, often citing Western sanctions on the Russians economy.

The US and other Western countries sanctioned Russia in 2014 over its illegal annexation of Crimea, a peninsula on the Black Sea in Ukraine.

But asked about those sanctions on Thursday, Putin said they were "because Russia is seen as a threat, because Russia is seen as becoming a competitor."

"It is clear to us that we have to defend our interests, and to do so consistently, not boorishly or rudely, in both the sphere of the economy and of defence," said Putin. "The pressure will end when our partners will be persuaded that the methods they are using are ineffective, counterproductive and harmful to all."

When asked whether "non-stop" sanctions could lead to World War III, Putin pulled an Albert Einstein quote to deliver a dark warning.

He said: "I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones," NBC News reports.

"A third world war could be the end of civilization," Putin went on, saying the high stakes "should restrain us from taking extreme steps on the international arena that are highly dangerous for modern civilization."

Perhaps more than any other country, Russia has the nuclear capability to end the world. With around 7,000 nuclear weapons, and the most diverse and destructive nuclear arsenal, Putin could unilaterally decide to embark on a civilization-ending war.

Additionally, by annexing Crimea, Putin changed land borders in Europe by force. The last time that happened was in the run-up to World War II.

But Putin also gave a nod to the force keeping his nuclear and military ambitions in check: mutually assured destruction. Basically, if Putin decides to let nukes fly, the US will respond in kind, destroying Russia as well.

"The threat of mutual destruction has always restrained participants of the international arena, prevented leading military powers from making hasty moves, and compelled participants to respect each other."

Putin then said the US withdrawing from a ballistic missile defense treaty would make Russia "respond."

So far, Putin's response has included building what experts call a nuclear "doomsday device," an underwater torpedo that could render large tranches of the world uninhabitable for decades.