An Israeli television report said on Tuesday that Iran is building a facility in northwest Syria to manufacture long-range rockets, and showed satellite images it said were of the site under construction.
Prime Minister Benjamin Netanyahu warned last week that Iran was strengthening its foothold in its ally Syria as Islamic State fighters were being displaced, and said Israel was watching developments and would act against any threat.
"Our policy is clear: We vehemently oppose the military buildup by Iran and its proxies, primarily Hezbollah, in Syria and we will do whatever it takes to protect Israel's security," he said in a speech.
The Channel 2 television news report showed images it said were taken by an Israeli satellite showing a site in northwest Syria near the Mediterranean coastal town of Baniyas, saying some of the construction indicated explosives would be stored there.
The images from the Eros B satellite showcase the site's ability to store underground missiles, the reports said.
It compared images of buildings it said were of a rocket factory near Tehran to structures at the Syrian site, and said there was a strong resemblance between them.
Netanyahu has been harshly critical of a 2015 deal that six world powers including the United States under then-president Barack Obama struck with Iran to curb its nuclear program in return for an end to multilateral sanctions.
Iran is Israel's avowed enemy, and Israel argues that the agreement fails to prevent Iranian weapons posing a threat to its very existence. Iran says its nuclear program is for peaceful purposes only.
The United States last month slapped new economic sanctions on Iran over its ballistic missile program and said Tehran's "malign activities" in the Middle East had undercut any "positive contributions" from the 2015 accord curbing its nuclear program.
U.S. President Donald Trump has frequently criticized the agreement as being too soft on Tehran, which remains subject to a UN arms embargo and other restrictions.
U.S. news reports have said that Israeli intelligence officials will discuss the situation in Syria and Lebanon with U.S. counterparts in Washington this week.
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