(Bloomberg) — Iran said Israel and the U.S. were likely behind the assassination of one of its top nuclear scientists on Friday and vowed revenge, sharply escalating tensions in the Persian Gulf in the final weeks of Donald Trump’s presidency.Mohsen Fakhrizadeh was the head of research and innovation at Iran’s Ministry of Defense, according to a government statement. He was killed close to the Damavand campus of Islamic Azad University, about 60 kilometers (37 miles) east of central Tehran, the semi-official Tasnim news reported.“Terrorists murdered an eminent Iranian scientist today. This cowardice—with serious indications of Israeli role—shows desperate warmongering of perpetrators,” Iranian Foreign Minister Mohammad Javad Zarif said in a tweet, without offering any evidence for Israel’s involvement.Iran’s army said the U.S. also bore responsibility, according to the Iranian Labor News Agency.Four other Iranian nuclear scientists have been killed since 2010, with Tehran usually blaming the intelligence agencies of its arch foes, Israel and the U.S.Zarif urged the international community to condemn the attack, while the head of Iran’s armed forces, Major General Mohammad Bagheri, called for the assassination to be avenged.The office of Israeli Prime Minister Benjamin Netanyahu declined to comment. Trump retweeted a New York Times report on Fakhrizadeh’s killing without comment.Israel’s leader had singled out Fakhrizadeh in an April 2018 presentation he gave on Iran’s nuclear program, claiming that the scientist was the director of a secret project to develop nuclear weapons.The United Nations nuclear watchdog, the International Atomic Energy Agency, has said “Project Amad” was mothballed in 2003, and Iran dismissed Netanyahu’s presentations at the time as “lies and war-mongering.”Spiraling TensionsThe assassination of Fakhrizadeh comes at a sensitive time in Iran as Trump’s defeat in the Nov. 3 U.S. election offers an opportunity to reset ties with the West after years of economic and military confrontation.It’s likely to trigger the sort of popular anger that followed the January assassination of Iranian General Qassem Soleimani in a U.S. drone strike ordered by Trump. Iran fired missiles at bases housing American troops in Iraq in response to that attack, causing no fatalities but raising fears of a slide to war between the two adversaries.Axios reported this week that Israel’s government had instructed the military to prepare for a possible U.S. strike against Iran during the remainder of Trump’s term, though it said the order wasn’t based on intelligence or an assessment that the U.S. would order an attack.Fakhrizadeh was also named in a March 2007 UN Security Council Resolution as having been involved in Iran’s “nuclear or ballistic missile activities.”Israel has vowed to take any measures necessary to prevent Iran obtaining nuclear warheads, weapons Tehran says it has never sought to develop.Friday’s killing comes close to the 10th anniversary of the assassination of another scientist, Majid Shahriari, who was killed in a car bomb on Nov. 29, 2010.Car BombingA number of Fakhrizadeh’s security guards were wounded in the attack, in which his car was shot at before a Nissan laden with explosives detonated about 15 to 20 meters away, Iran’s Minister of Defense Amir Hatami told state TV.Photos published by the semi-official Fars news agency, purportedly from the scene, showed blood splattered on tarmac next to an Iranian-made black passenger car with the window down on the driver’s side. The car’s windscreen had been shattered by several bullet holes.Hatami said Fakhrizadeh was involved in an air-defense project for detecting spy aircraft without using radar systems. Iran’s expanding missile program is a key concern for both the U.S. and Israel. But it’s the nuclear issue that has been to the fore.Iran broke limits on the amount of low-enriched uranium it was allowed to store under the 2015 nuclear deal with world powers after Trump exited the accord and imposed sweeping economic sanctions on the Islamic Republic.Tehran’s store of low-enriched uranium increased to about 2,443 kilograms (5,386 pounds) from 2,105 kilograms, according to the latest report by the UN monitors. That’s enough of the heavy metal to create three bombs if Iran chose to enrich the material to weapons grade.President-elect Joe Biden has said the U.S. could re-enter the nuclear agreement if Iran returns to compliance.For more articles like this, please visit us at bloomberg.comSubscribe now to stay ahead with the most trusted business news source.©2020 Bloomberg L.P.