WASHINGTON — The Trump administration on Monday imposed sanctions on 271 employees of the Syrian government agency it said was responsible for producing chemical weapons and ballistic missiles, an effort to impose a sweeping punishment after a sarin attack on civilians this month.
The sanctions on members of President Bashar al-Assad’s Scientific Studies and Research Center more than doubles the number of Syrian individuals and entities whose property has been blocked by the United States and who are barred from financial transactions with American people or companies.
Steven Mnuchin, the secretary of the Treasury, described it as one of the largest actions his department’s Office of Foreign Assets Control had ever undertaken. It seeks to punish those behind this month’s chemical weapons attack in Khan Sheikhoun and previous ones carried out by Mr. Assad’s government, and to deter others contemplating similar actions.
“The United States is sending a strong message with this action that we will not tolerate the use of chemical weapons by any actor, and we intend to hold the Assad regime accountable for its unacceptable behavior,” Mr. Mnuchin told reporters at the White House. “The Treasury Department, together with the Department of State and our international partners, will continue to relentlessly pursue and shut down the financial networks of any individuals involved with Syria’s production or use of chemical weapons.”
It is not clear what impact the restrictions will have, given that they only apply to business, financial holdings or transactions involving United States people or companies. Administration officials said they had focused on highly educated Syrian officials with deep expertise in chemistry who were thought to have the ability to travel extensively and possibly to use the American financial system.
“We wouldn’t be doing this if we didn’t think it was impactful,” Mr. Mnuchin said. “It’s quite impactful.”
It was the second time the United States government has imposed sanctions on Syrians for the government’s use of chemical weapons. In January, the Treasury Department blacklisted 18 Syrians, including six connected to the scientific studies center, after an investigation by the Organization for the Prohibition of Chemical Weapons, the international body that polices chemical weapons, determined that the government had been responsible for three chlorine gas attacks.
The Syrian government has portrayed the Scientific Studies and Research Center as a medical and agricultural study agency, but the United States government has long considered it a training ground and secret laboratory network for engineers developing chemical and biological weapons.
Britain applauded the American action, calling it a strong message that the use of chemical weapons is unacceptable.
“The abhorrent attack on Khan Sheikhoun is a stark reminder that the international community must work together to deter the future use of chemical weapons in any circumstances,” Boris Johnson, the British foreign secretary, said in a statement. “Sanctions send a clear signal that actions have consequences and seek to deter others from a similar acts of barbarism.”
But American officials have said this month’s attack indicated that the Assad government still had the capacity to make and use chemical weapons.
On Monday, one official said that assault and at least one other this month suggested that Syria had an ongoing chemical weapons program and called into question declarations the government had made to the contrary.
Republicans who had long criticized the Obama administration for doing too little to prevent the Assad regime’s atrocities also praised the sanctions.
“They represent another stark departure from the Obama administration’s dithering on Syria, which only worsened the bloodshed and created a vacuum for ISIS,” said Representative Ed Royce, Republican of California and the chairman of the Foreign Affairs Committee, referring to the Islamic State. He said he would push forward with Democrats on legislation that would “give the White House additional leverage to hold Assad — as well as his Russian and Iranian backers — accountable.”
A report issued by the National Security Council this month that included a declassified account of the Khan Sheikhoun attack said American intelligence had indicated that “personnel historically associated with Syria’s chemical weapons program” were at Shayrat airfield in March and on the day of the assault.
That airfield is believed to have been used by Syrian government warplanes to carry out the attack. President Trump ordered missile strikes on the airfield days later.
An administration official declined to say whether any of those figures were part of the group targeted with sanctions on Monday, citing the need to protect intelligence sources and methods, but asserted that those being blacklisted were believed to be responsible for attacks.