An operation to carry out strikes on Iranian territory had been jointly planned with the United States for several months, Israel’s Channel 12 reported, citing a security source.

The source claimed that Israel “will make every effort” in the operation and that the United States “shares the same position.” The source also said the “initial phase” of the joint attack is expected to last four days.

The Israeli outlet reports that the first strikes were carried out in the morning hours to “surprise” the Iranians, who were not expecting an attack in broad daylight.

U.S. President Donald Trump had previously stated that he was dissatisfied with the course of recent U.S.–Iran negotiations, that Iran must not possess nuclear weapons, and that it should not have uranium enrichment capabilities.

Yesterday, he said that “sometimes force has to be used.”