Russia said the use of a tactical nuclear weapon by the U.S. in Iran would be "catastrophic" after a report that it had not been ruled out as an option for President Donald Trump, who is considering joining Israel's strikes.

As Trump considers joining the war in the Middle East, Iran’s ally says there could be potentially perilous consequences for the world.

Russia has warned the United States not to provide direct military assistance to Israel as the two countries continue to bomb each other in a six-day conflict