A Syrian opposition news site reported Wednesday that the country’s embattled president, Bashar Assad, had recently visited a missile and chemical weapons research station run by Iran on Syrian soil.

The report followed an announcement by the Pentagon on Tuesday that it had detected “active preparations” by Syria for a chemical weapons attack, and a White House statement that the Syrian government would “pay a heavy price” if it carried out such an assault.

Quoting a non-government source with close ties to the White House, Zaman al-Wasl reported that the US administration had been tipped off that Syrian authorities were planning a possible sarin gas attack in either the east or south of Syria, where Assad’s forces and its backers have suffered recent setbacks against rebels in the sixth year of the civil war.

Assad is believed to have used sarin gas in an weapons attack that killed dozens of people in Idlib province on April 4, as well as in early attacks on civilians since the war began.

Syrian children receive treatment following a suspected toxic gas attack in Khan Sheikhun, a rebel-held town in the northwestern Syrian Idlib province, April 4, 2017. (AFP/Mohamed al-Bakour)

Syrian children receive treatment following a suspected toxic gas attack in Khan Sheikhun, a rebel-held town in the northwestern Syrian Idlib province, April 4, 2017. (AFP/Mohamed al-Bakour)

Times Of Israel

The station, to be inaugurated by the end of this year, works on developing long-range missiles and is located in a valley between the Hama and Tartus provinces, close to the Syrian border with Lebanon, the report said.

The report said Assad’s visit to the station followed a rare stop in the historically anti-Assad city of Hama, some 213 kilometers (132 miles) north of Damascus, where he delivered prayers for Eid al-Fitr, marking the end of the Ramadan fast.

The visit to Hama indicated that the Syrian leader was feeling more confident about his position.

Responding to the Pentagon’s assessment, Russian President Vladimir Putin’s spokesman Dmitry Peskov said Tuesday that “such threats to Syria’s legitimate leaders are unacceptable.”

Russia is Assad’s key backer and sided with him when he denied responsibility for the April chemical attack in Idlib province.

That attack was followed by a US cruise missile strike on a Syrian government air base.