The USA is worried about China and Russia developing hypersonic missiles. These can travel 20 times the speed of sound. The U.S. military said hypersonic missiles are a security problem for the USA. It warned that the USA could not stop Russia or China using these missiles. It needs its nuclear weapons. U.S. President Donald Trump plans to meet with Russian President Vladimir Putin soon to talk about the arms race.

Russia tested a hypersonic missile this month. China tested some last year. President Putin said Russia needed the weapons because "unlawful sanctions" from the USA and Europe have hurt Russia's development. He added: "You have failed to contain Russia." Mr Putin says the missiles can "strike like a fireball". Relations became worse this week after the UK and USA expelled Russian diplomats because of the poisoning of a Russian spy in England.