Syrian soldiers may have used chemical weapons in a recent lethal attack without receiving permission from President Bashar Assad, the German paper Bild am Sonntag reported Sunday, as the US pushed on with efforts to rally support for a military strike against Syria.

The paper said that Germany’s intelligence services had intercepted a number of radio transmissions over the past four months, in which officers had asked Assad for permission to use gas — and had always been turned down. It said the requests had come from brigade and division commanders, and that most of the communications were intercepted by a naval vessel sailing off the Syrian coast.

The August 21 attack caused an international uproar over the use of chemical weapons against civilians, and appeared to cross what US President Barack Obama had said was a “red line” that would force the world to take action in Syria.

In almost two-and-a-half years of fighting, over 100,000 people have been killed and some two million have fled Syria. However, the August attack was the first incident in which chemical weapons were used on a large scale in the civil war.

The issue was taken to the UN Security Council, where Russia and China blocked attempts by France, the US and Britain to pass a resolution that would enable them to use force against the Syrian regime. British Prime Minister David Cameron asked his parliament for permission to take part in a military effort against Assad, but was turned down.

The Obama administration, for its part, has been making a big push to rally members of Congress and the international community. Lawmakers are this week to consider a resolution authorizing the “limited and specified use” of US armed forces against Syria for no more than 90 days and barring American ground troops from combat.

The White House asserted Sunday that a “common-sense test” rather than “irrefutable, beyond-a-reasonable-doubt evidence” makes the Syrian government responsible for the chemical weapons attack.

As part of a major push to win the backing of a divided Congress and skeptical American public, Obama’s top aides made the rounds of the Sunday talk shows to press the case for “targeted, limited consequential action to deter and degrade” Assad’s capabilities “to carry out these terrible attacks again.”

At the same time, White House chief of staff Denis McDonough acknowledged the risks that military action could drag the US into the middle of a brutal civil war and endanger allies such as Israel with a retaliatory attack.

The US is “planning for every contingency in that regard and we’ll be ready for that,” he told CNN’s “State of the Union.”

The US, citing intelligence reports, said sarin gas was used in the August 21 attack outside Damascus, and that 1,429 people died, including 426 children. The Britain-based Syrian Observatory for Human Rights, which collects information from a network of anti-regime activists, says it has so far only been able to confirm 502 dead.

The Syrian government denies responsibility, contending rebels were to blame.

Obama plans a national address Tuesday night from the White House on Syria, and McDonough was asked whether the president would reveal a direct connect between Assad and the attack.

“The materiel was used in the eastern suburbs of Damascus that have been controlled by the opposition for some time,” McDonough said. “It was delivered by rockets — rockets which we know the Assad regime has and we have no indication that the opposition has.”

McDonough also cited a DVD compilation, released Saturday by a US official, of videos showing attack victims. The DVD was shown to senators during a classified briefing on Thursday.

“We’ve seen the video proof of the outcome of those attacks,” he said. “All of that leads to a quite strong common-sense test irrespective of the intelligence that suggests that the regime carried this out. Now do we have a picture or do we have irrefutable beyond-a-reasonable-doubt evidence? This is not a court of law and intelligence does not work that way. So what we do know and what we know the common-sense test says is he is responsible for this. He should be held to account.”

Recent opinion surveys show intense public skepticism in the US about military intervention in Syria, even among those who believe Syria’s government used chemical weapons on its people.

Speaking at a press conference in Paris, US Secretary of State John Kerry said the videos make clear that the attack was not something Americans can ignore.

“Those videos make it clear to people that these are real human beings, real children, parents being affected in ways that are unacceptable to anybody, anywhere by any standards,” Kerry said. “And the United States of America that has always stood with others to say we will not allow this — this is not our values, it’s not who we are.”

Kerry is in Europe trying to raise European support for a strike in Syria and discussing Middle East peace negotiations.