The British Navy's nuclear submarine HMS Anson is in the northern Arabian Sea, The Mail on Sunday reported, citing military sources.
It is noted that the submarine could be used in the US military operation against Iran if necessary.
An air defense system has been activated in Tehran amid another air strike on the Iranian capital, Mehr news agency reported.
The Israeli Defense Forces have launched strikes on the Iranian capital, the army press service reported earlier.
Numerous explosions have occurred in almost all parts of Tehran, according to the Al-Hadath TV channel.
Several missile launchers of the Iranian army were bombed in the city Yazd, located in central Iran, Iranian state television reported.