Israel's political-security cabinet convened on Wednesday morning to discuss a possible U.S. strike on Syria, a day after Prime Minister Benjamin Netanyahu warned that Israel would respond with force if it came under attack.

Meanwhile, Foreign Policy reported that the U.S.' proof that Bashar Assad's regime is responsible for the deadly chemical attack last week is intercepted phone conversations between senior Syrian officials.

According to the report on Tuesday, hours after the attack a Syrian Defense Ministry official made "panicked phone calls" to a commander of a chemical weapons unit, "demanding answers for a nerve agent strike that killed more than 1,000 people."

Also on Wednesday, a team of United Nations inspectors left their Damascus hotel and headed to the scene of an alleged chemical weapons strike on several suburbs outside the capital last week, a Reuters witness said.

Opponents of Assad say his forces used rockets loaded with poison gas in the middle of a fierce offensive on the Damascus outskirts, with activists putting the death toll between 500 and more than 1,000. Assad denies the charges.