U.S. officials have been told Israel is fully ready to launch an operation into Iran, multiple sources told CBS News.

Israel and Iran have begun a new round of attacks, as the conflict between the two heavily armed rivals enters its fourth day.

"This confrontation will not end with last night's limited actions and Iran's strikes will continue, and this action will be very painful and regrettable for the aggressors," Fars reported, citing senior military officials.

This is the second time President Trump and Russian President Vladimir Putin have spoken on the phone this month.