The United States on Thursday carried out targeted missile strikes in Syria in response to the deadly chemical attack that killed dozens in the country’s rebel-held Idlib province. The Syrian Army has said that the strike had killed six personnel and caused “big material losses”, Reuters reported.

Described as the “toughest direct action” by Washington so far, the strikes have risked retaliation from Syrian allies Russia and Iran. On Friday, Russian President Vladimir Putin 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. However, the strike has been backed by several countries, including the United Kingdom and Australia.

US President Donald Trump said, “Tonight [on Thursday], I ordered a targeted military strike on the airbase in Syria from where the chemical attack was launched. It is in the vital national security interest of the United States to prevent and deter the spread and use of deadly chemical weapons.”

The US had blamed the Bashar al-Assad government for the gas attack. “Years of previous attempts at changing [Syrian President] Assad’s behavior have all failed and failed very dramatically,” Trump said.

A military official said 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 Washington Post quoted the official as saying. He added that the Russian Army was informed of the strike to prevent any damage and no Russian jets were found at the site of the strikes.

On Thursday, Trump had said that the poison gas attack which killed at least 80 people had “crossed a lot of lines” for him but that he would not reveal what he planned on doing militarily. He also blamed his predecessor, Barack Obama, for imposing “weak policies”. “President Obama had said in 2012 that he would establish a ‘red line’ against the use of chemical weapons and then did nothing,” Trump had said.

Also on Thursday, Turkey said postmortem results of the victim’s bodies confirmed that chemical weapons were used in the attack. Syria, however, has continued to maintain that their armed forces did not use chemical weapons in the attack.

In September 2016, the Syrian government was accused of dropping barrel bombs containing chlorine that killed more than 80 civilians in the Sukari area of Aleppo.