United States intelligence agencies are alarmed by a series of cargo flights from Iran to Syria that they believe could be transporting weapons systems that could threaten Israel, CNN reported Wednesday.

While CNN noted that flights between Iran and Syria are not uncommon, the flights concerning U.S. intelligence occurred in the aftermath of U.S.-led airstrikes against Syrian chemical weapons facilities earlier this month.

On Monday, social media sites that track air traffic picked up two flights from by Syrian Air Force cargo jets flying to Syria from Iran. An administration official told CNN that there have been other similar flights including at least one Iranian cargo plane.

Before the U.S.-led attack against Syria’s chemical weapons stores, an airstrike targeted the Tiyas or T-4 airbase in Syria, where Iran had personnel and advanced weapons. The T-4 airstrike was attributed to Israel and seven Iranian military personnel were killed in the airstrike.

Since the attack on T-4, Iranian officials have stepped up their anti-Israel rhetoric and threatened revenge against Israel.

Last week, Iranian Foreign Ministry Spokesman Bahram Qassemi said that Israel would receive “required responses sooner or later,” and that Israel “cannot take (such) an action and be exempt from punishment.” A few days earlier, Iranian Army Ground Forces commander Brigadier General Kiumars Heidari said that Israel can no longer attack Iran and that the date has already been set for Israel’s destruction.

Two Iranian officials also threatened to destroy Tel Aviv and Haifa, two of Israel’s largest cities.

This past Saturday, Major General Abdolrahim Mousavi, commander of Iran’s army, threatened that Iran’s regular army and Iran’s Islamic Revolutionary Guard Corps (IRGC) would combine to “annihilate” Israel within 25 years.

CNN reported that Ali Shamkhani, the Secretary of Iran’s Supreme National Security Council, and former defense minister, similarly threatened Israel. He said, “There will definitely be a punishment of the aggressor but naturally, the time, place and quality of the response to this vicious act depends on the Islamic Republic’s will and choice.”

An IRGC colonel, who was killed in the T-4 airstrike, was reportedly in charge of Iran’s drone program. In February, a drone launched from T-4, penetrated Israeli airspace, before being shot down. Israel recently announced that the drone was loaded with explosives and was meant to carry out an attack on Israeli soil.

[Photo: Persian Boy / YouTube ]