A Russian S-400 is delivered to Turkey.

TEL AVIV: Israeli air strikes against targets in Syria may be one of the main reasons for the growing crisis between Russia and Turkey since they’re highlighting the Russian-made S-400 air defense systems may not be as effective as Turkey believed.

The first signs of dissatisfaction with the Russian air defense systems came on May 1 when the Syria Direct website ran a story quoting what was described as a Syrian military source who criticized the S-300 air defense systems supplied by Russia. The source pointed to the repeated failures of the Russian-made systems to protect sites in Syria from the Israeli strikes. The comments by the apparent Syrian military official was the first clear sign of a big dispute between Moscow and Ankara related to the operational efficiency of the air defense systems.

Turkey has signed a deal with Russia to purchase S-400 systems in a deal worth more than $1 billion. The first systems have already been supplied to Turkey but they are not operational yet.

Last year, the Israeli air force hit more than 200 targets in Syria connected to the Iranian effort to upgrade  Hezbollah’s rockets. Some of those attacks have been reported to involve Israeli F-35s. The attacks continue apace this year with Syrian air defense forces having launched more than 1,000 surface-air missiles to try and foil the repeated Israeli attacks. They’ve had little effect so far.

The latest attack was Thursday. According to the Syrian Center for Human Rights, at least nine people were killed, four of them Syrians and five of whom are unknown at this time. Reportedly, the number may go up. The Lebanese Al-Miyadin channel, which is close to Hezbollah, reported that Israeli planes attacked four targets and returned to Israel. Israeli aircraft attacked Syrian regime security factories and destroyed weapons depots, according to the Syrian Center for Human Rights.

Washington ejected Turkey from the F-35 program because of President Erdogan’s decision to go ahead with the S-400 deal. While it accepted delivery of at least one, Turkey has delayed ordering additional S-400 batteries.

An Israeli expert who spoke on condition of anonymity said the U.S has been put in an almost impossible situation.

“The Turkish government spat in the face of the U.S by buying the Russian-made missiles. The retaliation was fast. But the reality these days is very complicated, a fact that forces Washington to make two steps backward. When you have nuclear weapons on Turkish soil, a request for Patriot missiles (made by Erdogan in March) cannot be turned down.” Syria did manage to down an Israeli F-16 in February 2018, but the Israeli military later said the crew made an error when threatened.

Tal Inbar, an Israeli defense analyst, told Breaking Defense that the S-300 and S-400 have never been proved in action against advanced fighters. “In addition the S-400s in Turkey are not operational,” he noted, “so Ankara asked for the Patriots.”