A Syrian opposition website claimed on Wednesday that President Bashar al-Assad recently visited an Iranian-run chemical weapons and missile production facility, The Times of Israel reported.

The website, Zaman al-Wasl, cited a source reportedly with close ties to the White House who said that the U.S. administration is aware of plans by the Assad regime to launch a chemical weapons attack in the south or east of the country, where Assad’s forces have recently suffered setbacks.

Assad reportedly visited the facility, located near the border with Lebanon, in the past week. The facility is meant to produce long range missiles and set to be inaugurated by the end of the year.

The Trump administration released a statement Monday warning the Assad regime that it would “pay a heavy price” if it launched another chemical attack against civilians. The administration reportedly issued the warning after it detected activity at the Shayrat airbase in western Syria, similar to the activity seen at the base prior to an April sarin gas attack in Idlib province, which killed at least 87 civilians.

The U.S. fired 59 Tomahawk missiles at Shayrat in response to the chemical attack in April

It is unclear if Assad’s reported visit to the Iranian facility was a factor in the administration’s warning.

After the Idlib chemical attack, Benjamin Weinthal reported for The Jerusalem Post that Iran had played a significant role in developing Syria’s chemical weapons program. In August 2013, the Assad regime also used sarin gas in an attack on the rebel-held suburbs of Damascus, killing 1,429 people, including 426 children, according to U.S. intelligence.

[Photo: Syrian Arab News Agency]