David Jackson

USA TODAY

WASHINGTON — The White House said Tuesday there is overwhelming evidence that Syria used a sarin nerve agent to attack opponents of the government last week, and that Russia is trying to help Bashar Assad's government cover up this illegal use of chemical weapons.

"The Syrian regime and its primary backer, Russia, have sought to confuse the world community about who is responsible for using chemical weapons against the Syrian people in this and earlier attacks," said a report issued by the National Security Council.

The NSC report said Syria's use of chemical weapons is "unacceptable" and poses a "clear threat" to the United States and the world. It called on the international community to make a statement that "this behavior will not be tolerated," though it did not specify possible consequences.

While not specifically mentioning Russia in its call for action, the report said: "This is a critical moment — we must demonstrate that subterfuge and false facts hold no weight, that excuses by those shielding their allies are making the world a more dangerous place."

The report and three White House officials, speaking on condition of anonymity to discuss classified information, said the Syrians and its backers with the Russian government are trying to cover up the use of chemical weapons with false narratives.

Both countries have claimed that investigators are using old or fake videos and that opposition forces had a depot of chemical weapons that may have been struck during the attacks, claims that U.S. officials said do not withstand scrutiny.

The Russian government is trying to cover up, one Trump administration official said, and is engaging in a clear pattern of deflecting blame from Syria.

While some U.S. officials believe Russians may have had pre-knowledge of the chemical weapons attack, the report did not allege that. "There's no consensus within the intelligence community," White House spokesman Sean Spicer said.

Spicer also created an instant controversy by comparing Assad to Adolf Hitler, saying at least the German dictator did not use sarin on his own people. He did, however, lead the Holocaust that killed at least 6 million Jews across Europe, many of them gassed in concentration camps.

"We didn't use chemical weapons in World War II. You had a — someone who is as despicable as Hitler who didn't even use chemical weapons," Spicer said. "You have to, if you're Russia, ask yourself, is this a country and regime you want to align yourself with?"

President Trump has not commented publicly in recent days on next steps in Syria, though aides have said he is prepared to strike them again if Assad's government again uses chemical weapons.

The president did, however, suggest he would not go to war, telling Fox Business Network that "we are not going into Syria."

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The cruise missile strike against a Syrian air base destroyed some buildings and warplanes, but the runway was left intact, and Syrian planes flew from there days later.

The NSC released its report as Secretary of State Rex Tillerson visited Moscow.

Hours before the Trump administration released its findings, Putin accused the United States of planning more missile strikes on Syria and of using fake "false flag" chemical weapons attacks as a pretext.

"We have information that a similar provocation is being prepared," the Russian president said, offering no evidence for his claim.

Spicer said Russia is isolated within the world community over its support of Syria, and that "Russia is on an island."

The Trump administration has a complicated relationship with Russia.

The president's critics have accused him in recent months of trying to cozy up to Putin. They cited ongoing investigations of possible contacts between Trump's presidential campaign last year and Russians who sought to influence the election in Trump's favor.

Trump supporters said there is no special relationship between the president and Putin, and the Syria dispute proves it. Eric Trump, the president's son, told The Telegraph that "if there was anything that Syria did, it was to validate the fact that there is no Russia tie."

According to the National Security Council report, the attack began around 6:55 a.m. on April 4 in the town of Khan Shaykhun and led to "at least 50 and up to 100 fatalities."

Victims' accounts, videos, hospital records, and an analysis by the World Health Organization of people's symptoms in the hours after the attack point to the use of sarin, officials said.

The opposition could not have fabricated these videos and reports in so short a time, the NSC report said, because doing so "would have required a highly organized campaign to deceive multiple media outlets and human rights organizations while evading detection."