Politico: US ups intelligence, surveillance measures in response to Russian nuclear threats

Russia is being monitored closely for any signs of an order given by Russian dictator Vladimir Putin to use nuclear weapons in Ukraine, Politico reports, citing five unnamed current and former U.S. officials.

Although the preparation of Russia's intercontinental ballistic missiles will give off more obvious signs, Russia is able to arm their aircraft conventional rocket and missile systems with smaller nuclear arms without much warning, the officials reportedly said.

Putin's threat of a nuclear strike on Ukraine or even NATO, long dismissed as a bluff, is beginning to be taken more seriously after he stressed that attacks on Ukrainian territories annexed by Russia in sham referendums would be considered as attacks on Russia itself.