Washington PostWASHINGTON ó President Donald Trump said Monday that his administration would be making "major decisions" about its response to a suspected chemical attack in Syria within the next 24 to 48 hours, decrying the action as "atrocious" and "horrible.""We are very concerned when a thing like that can happen," Trump said at the outset of a Cabinet meeting while reporters were present. "This is about humanity, and it canít be allowed to happen."U.S. officials said Sunday that they were weighing options to strike Syrian government targets after at least 40 people were killed in the opposition-held town of Douma, roughly 10 miles from Syriaís capital, Damascus.Trump said Sunday on Twitter that there would be a "big price to pay" for the attack. His comments on Monday were his first publicly spoken remarks on the subject."If itís the Russians, if itís Syria, if itís Iran, if itís all of them together, weíll figure it out," Trump said.Russian Foreign Minister Sergei Lavrov said Monday that Russian aid workers had visited the area and found no evidence that chemical weapons were used.Russia is Syriaís main military partner and ally and has protected Syrian President Bashar Assad both militarily and diplomatically for years.Russia helped the United States negotiate an agreement with Assad five years ago that was supposed to rid the country of chemical weapons, and the United States and other nations have held Russia responsible for allowing Assad to retain and use these weapons.Asked by a reporter if he had any doubt who was behind the attack, Trump said: "To me thereís not much a doubt, but the generals will figure it out."He said "nothing is off the table" when asked if U.S. military action is an option.Trump said it has been "very hard to get people in" to determine what happened, which he said was a sign of Syriaís culpability.Meanwhile, the U.N. human rights chief warned Monday of the dangers of a "collective shrug" and "impotent" international response to the possible use of chemical weapons in Syria over the weekend. Zeid Raíad al-Hussein said the world and veto-wielding Security Council powers need to "wake up fast to the irreparable damage" being done to international efforts to ban use of weapons of mass destruction. His office in Geneva says it has a lack of information about the purported chemical weapons attack in Douma, but it pointed to nearly three dozen chemical attacks in Syria since the country ratified the Chemical Weapons Convention 41/2 years ago. A total of 192 states have ratified the agreement that prohibits the use of chemical weapons, making it one of the most universally accepted conventions. Zeid faulted "ineffectual, or deliberately obstructive, global leadership" on chemical weapons, and said some "very powerful states" involved in Syriaís conflict have failed to halt "this ominous regression toward a chemical weapons free-for-all." Russia voted for the cease-fire but has repeatedly used its veto power as a permanent member to block any measure that threatens a Syrian offensive against rebels, largely to protect the government of Assad.Russia wants to preserve access to its only naval base in the Middle East and preserve its influence in the region through Assad.Information from the Associated Press was used in this report.