The Wall Street Journal reports: The Syrian army has used lethal chemical weapons during the country’s civil war, Israel’s top military intelligence analyst said Tuesday, heightening pressure on the White House to intervene more directly against strongman Bashar-al Assad.

“According to our professional assessment, the regime has used deadly chemical weapons against armed rebels on a number of occasions in the past few months,” said Brig. Gen. Itai Brun, who heads the research division of Israel’s intelligence branch.

Israel’s first public allegation of Syrian chemical-weapons use followed disclosures last week that Britain and France believe they have credible evidence that Syria has used chemical weapons in small amounts.

U.S. officials said they were investigating the allegation. But they quickly voiced strong caution about the assessment—which, if borne out, could force the U.S. to make good on its threats to take action if Syria’s government were to use chemical weapons against its people. A senior U.S. defense official played down what he called “low-confidence assessments by foreign governments” and said it would take time to reach a U.S. determination that could be the basis for U.S. action.

That sharp response appeared to convey a U.S. government caught off guard. Gen. Brun delivered his assessment at a security conference in Tel Aviv just as U.S. Defense Secretary Chuck Hagel was wrapping up two days of meetings with Israel’s civilian and military leaders. His agenda was topped by talks on Iran and on strengthening coordination over the security of Syria’s chemical weapons.