Soldiers have joined a mass rally in the North Korean capital Pyongyang, after leader Kim Jong-un stepped up threats against the US.
He has signed off an order, putting missile units on standby to attack American bases in neighbouring South Korea and the Pacific.
Russia says it is worried about increased military activity near North Korea, an apparent reference to joint drills being run by Washington and Seoul.
“We are concerned that, along with this adequate reaction of the Security Council, along with the collective reaction of the world community, unilateral actions are being taken around North Korea, which are manifested in the build-up of military activity,” said Sergey Lavrov, Russian Foreign Minister, at a news conference in Moscow.
“The situation may slip out of control and fall into a vicious circle.”
North Korea made its latest threats after the US flew two nuclear-capable stealth bombers over the Korean peninsula.
A propaganda video animation, posted on the internet, is said to show a North Korean missile destroying one of those planes.
Few believe that Pyongyang will risk starting an all-out war.
The full video animation is available to watch below.