Potential use of tactical nuclear weapons by the United States in Iran would be a catastrophic development, Russian state news agency TASS quoted Kremlin spokesman Dmitry Peskov as saying on Friday. Peskov was commenting on what he called speculative media reports about that possibility. His comments, as reported by TASS, did not mention any media by name.

The Guardian newspaper reported that U.S. defence officials were briefed that using conventional bombs against Iran's underground uranium enrichment facility at Fordow would not be enough to destroy it completely, and that destroying it would require initial attacks with conventional bombs and then dropping a tactical nuclear weapon from a B-2 bomber.

However, the British newspaper said President Donald Trump was not considering using a tactical nuclear weapon on Fordow and the possibility was not presented by Defense Secretary Pete Hegseth and the chairman of the Joint Chiefs of Staff, General Dan Caine, in meetings in the White House Situation Room.

Trump said on Thursday that any decision on potential U.S. involvement in the Israel-Iran conflict would be made within two weeks.

Russia, which has close ties with Iran, has warned strongly against U.S. military intervention on the side of Israel.