LONDON — Moscow accused Israel of "hostile" behavior and threatened retaliation Tuesday after Syria shot down a Russian military aircraft with 15 people on board over the Mediterranean Sea.

Russia is an ally of both Syria and Israel.

The TASS news agency reported that Russia's Defense Ministry said the Il-20 reconnaissance aircraft was brought down by Syrian anti-aircraft batteries after it was used as a shield by Israeli F-16 jets.

"We regard the provocative actions of Israel as hostile," Defense Ministry spokesman Igor Konashenkov was quoted as saying by TASS. "Fifteen Russian servicemen died as a result of the irresponsible actions of the Israeli military. This is absolutely not in keeping with the spirit of the Russian-Israeli partnership.”

He added that Russia reserves the right to retaliate, but did not specify how.

But Dmitry Peskov, the spokesman for President Vladimir Putin, stopped short of blaming Israel for the incident.

Russian President Vladimir Putin visits the Hmeymim Air Base near Latakia, Syria, on Dec. 11, 2017. Sputnik / EPA file

Israel's military later offered condolences over the Russian deaths but said the Syrian government should be held "fully responsible" for the incident.

Moscow said its plane disappeared from radar screens as it came in to land at the Hmeymim air base near Latakia in western Syria late Monday, at the same time as Israeli jets and French naval vessels were mounting airstrikes on targets in the same area.

According to the Russian Defense Ministry, the Israeli F-16 jets carrying out the airstrikes used the Russian plane as a cover to allow them to approach their targets on the ground without being hit by Syrian anti-aircraft fire.

Moscow said Israel did not warn Russia of its operation in the area until one minute before the strike.

The Russian military said the Syrian missiles were aimed at four Israeli fighter jets that were attacking targets in the coastal province of Latakia late on Monday.

A Syrian facility "from which systems to manufacture accurate and lethal weapons were about to be transferred on behalf of Iran to Hezbollah in Lebanon" was being targeted at the time of the incident, the Isreal Defense Forces said in a statement. "These weapons were meant to attack Israel, and posed an intolerable threat against it."

Israel will share all the relevant information with the Russian Government to review the incident and to confirm the facts in this inquiry. — Israel Defense Forces (@IDFSpokesperson) September 18, 2018

Russia and Israel have worked to improve ties and coordinate military operations.

Israel has appealed to Russia to help limit the influence of Iran and the Tehran-backed Lebanese group Hezbollah in Syria. In response, Russia has pledged to keep Iranian forces 50 miles away from Syrian borders with Israel, although this fell short of Israel’s demands for a full Iranian exit.

Russia has also been a key backer of Syrian President Bashar al-Assad and it has two military bases in the country, including one close to the Mediterranean coast.

Russia's military operation in Syria, which began in late 2015, has turned the tide of the conflict in favor of Assad as he battles against rebels.

Yuliya Talmazan and F. Brinley Bruton reported from London, Paul Goldman from Tel Aviv, and Elena Holodny from Moscow.