Reuters reported, citing a current U.S. official and two former U.S. officials, that over the past year the United States received several warnings from Israel about the Islamic Republic’s intent to assassinate Donald Trump, the U.S. president, but U.S. intelligence agencies were unable to independently verify those warnings.

According to the report, the most significant warning was delivered ahead of the NATO summit in Ankara. Israel had informed the White House that the Islamic Republic might target Trump during his trip aboard Air Force One using a shoulder-launched missile. Although the CIA did not find independent evidence to confirm this assessment, for precaution the U.S. Secret Service moved Trump to another military aircraft in a classified operation.

Reuters wrote that in several instances, the CIA assessed Israel’s information about threats attributed to the Islamic Republic, including plots to assassinate Trump, as having “low confidence.” However, that information was taken into account in the Trump administration’s security decision-making.