The US government is concerned that Israel is preparing to take military action against Iran over US objections, and has stepped up contingency planning to safeguard US facilities in the region, The Wall Street Journal reported.
The newspaper said President Barack Obama, Defense Secretary Leon Panetta and other top officials have delivered a series of private messages to Israeli leaders, warning about the dire consequences of a strike.
Obama spoke by telephone on Thursday with Israeli Prime Minister Benjamin Netanyahu, and General Martin Dempsey, chairman of the Joint Chiefs of Staff, will meet with Israeli military officials in Tel Aviv next week, the report said.
The Journal noted that the US military was preparing for a number of possible responses to an Israeli strike, including assaults by pro-Iranian Shiite militias in Iraq against the US Embassy in Baghdad.
Up to 15,000 US diplomats, federal employees and contractors still remain in Iraq.
To deter Iran, the United States is maintaining 15,000 troops in Kuwait, and has moved a second aircraft carrier strike group to the Persian Gulf area, the paper said.