Bashar al-Assad’s regime is planning another chemical attack in Syria, the White House said on Monday night, and warned the Syrian President that he would pay “a heavy price” if it took place. “The United States has identified potential preparations for another chemical weapons attack by the Assad regime that would likely result in the mass murder of civilians, including innocent children,” read the statement.

The US added that Russia and Iran – allies of Assad – would also have to share the burden of responsibility for such an attack. “Any further attacks done to the people of Syria will be blamed on Assad, but also on Russia and Iran who support him killing his own people,” tweeted US ambassador to United Nations Nikki Haley.

The Syrian government has not responded to the statements, reported BBC.

On April 4, at least 80 people were killed in a suspected chemical attack in the rebel-held Idlib province of Syria. The US blamed it on the Assad regime and Trump said that the poison gas attack had “crossed a lot of lines” for him.

On April 7, Trump had ordered missile strikes in Syria in response to the chemical attack. A military official had said that 59 Tomahawk cruise missiles were used to target the fighterjets and other infrastructure at the Al Shayrat airfield in Syria. The US missiles did not target anything that may have stored chemical weapons. The Russian Army was informed of the strike to prevent any damage and no Russian jets were found at the site of the strikes.

Described as the “toughest direct action” by Washington so far, the strikes have risked retaliation from Syrian allies Russia and Iran. Russian President Vladimir Putin had called the move illegal and warned that it would significantly hurt US-Russia ties. The Kremlin had earlier dubbed the strikes an “aggression against a sovereign state” and a violation of international law.