Al Jazeera.com - Russia has started delivering S-300 surface-to-air missile systems to Syrian forces, Russian Foreign Minister Sergei Lavrov said.


Lavrov told a news conference at the United Nations (UN) on Friday that "the delivery started already" after a decision was reached following�downing�of a Russian Il-20 reconnaissance aircraft which was hit by a Syrian missile.


Moscow said Israel was culpable as the Il-20 was caught in the crossfire as four Israeli fighter jets attacked targets in northwestern Syria.


The Israeli military said that Syria's indiscriminate air defence fire was the cause of the incident.

"As President [Vladimir] Putin said, after that incident ... the measures that we will take will be devoted to ensuring 100 percent safety and security of our men," said Lavrov.

The move comes in defiance of opposition from the United States and Israel.

US National Security Advisor John Bolton called Moscow's decision a "major mistake".

"We think introducing the S-300s to the Syrian government would be a significant escalation by the Russians and something that we hope, if these press reports are accurate, they would reconsider," he said on Monday.

In a phone call, Israeli Prime Minister Benjamin Netanyahu told Putin that "transferring advanced weapons systems into irresponsible hands will increase the dangers in the region", according to the Israeli prime minister's office.

Syrian Foreign Minister Walid Muallem said on Friday he hoped the missile system would help close the country's sky for Israeli warplanes.

Friendly fire

The downing of the reconnaissance plane was the worst case of friendly fire between Russia and Syria since Moscow's military intervention in the country in support of President�Bashar al-Assad's forces in September 2015.

Israel has carried out about 200 air raids in the last two years, according to its officials.

Since intervening in�Syria's war, Russia has generally turned a blind eye to Israeli attacks inside the country.�Israel and Russia have maintained a special hotline to prevent their air forces from clashing in the skies over Syria.

Israeli military officials have previously praised its effectiveness.

A dispute between Israel and�Russia�could restrict Israel's ability to mount air raids inside Syria on what it considers the greatest threat to its security from the Syria conflict: the build-up of Iranian forces or Iranian-backed�Hezbollah�fighters.