A mysterious blast heard in central Israel appears to have come during a rocket engine test conducted at a secretive military base associated with the country’s missile program, according to an analyst and satellite images.

Video of the incident at Sdot Micha Air Base circulated online last week. Iranian state media seized on it amid its tensions with Israel after a series of attacks targeting its nuclear program and amid negotiations in Vienna over its tattered atomic accord.

However, the smoke and flames filmed April 20 appear to be from a rocket engine test, said Jeffrey Lewis, an expert at the James Martin Center for Nonproliferation Studies at the Middlebury Institute of International Studies, who located the site with others. Lewis said the image compared to others of similar tests he and experts have extensively studied.

Satellite photos taken by Planet Labs Inc. and analyzed by The Associated Press of a known rocket test stand at Sdot Micha showed char marks and foliage burned away at the site after April 20. However, the surrounding buildings bore no signs of damage. The location also mirrored details of the video posted to social media.

The Israeli Defense Ministry did not immediately respond to questions from the AP.

Tomer, an Israeli government-owned company, told the AP on Sunday the blast came from “a conventional, controlled test in accordance with the working plan.”

The incident came just after Israel and the U.S. announced in February they would begin work on a new generation of interceptor missiles called the Arrow-4. Tomar on its website describes itself as producing the “rocket motors of the Arrow missiles, Shavit satellite launchers, ELRAD air defense systems and artillery rockets.” Such test-stand experiments often involve new systems.

Tomer declined to comment on whether the test involved the Arrow.

Israel hopes to replace its Arrow-2 missiles for the Arrow-4. The missiles, fired out of canisters, intercept and destroy ballistic missiles. The Arrow missiles are key to Israel’s defense from the ballistic missile program of Iran, Israel’s regional archenemy. In a February statement, Israeli Defense Minister Benny Gantz said the Arrow-4 would provide Israel with a “technological and operational leap forward, preparing us for the future battle field and evolving threats in the Middle East and beyond.”

The air base, some 35 kilometers (21 miles) southeast of Tel Aviv, includes a system of bunkers and underground facilities, some built with assistance from the U.S. government. Defense analysis firm Janes believes the air base also is home to Israel’s nuclear weapon-capable Jericho ballistic missiles. Under its policy of nuclear ambiguity, Israel neither confirms nor denies having atomic weapons though it is widely believed to possess them.

(AP)