A US military strike against Syria, if implemented, would be the "most directionless" action taken by Washington in its Middle East policies over the past six decades, Chinese observers said.

Ye Hailin, an expert on Middle East studies at the Chinese Academy of Social Sciences, said such an attack would be illogical and not in line with US interests in the region.

Protesters march on Saturday in Boston during a demonstration against a possible US-led military attack on Syria. US President Barack Obama announced he would seek congressional approval for such a move. Michael Dwyer / Associated Press

"This is the most directionless move in Washington's Middle East policies since Britain and France retreated from the region after World War II," Ye said.

"The Obama administration reached the conclusion that Syria used chemical weapons, although it did not send investigators there. Also, its judgment was based on video footage, not on uncontaminated physical evidence," he said.

Meanwhile, UN investigators are still working on samples collected at the scene and have not yet reached a conclusion, Ye said.

"And now that the Obama administration says it has reliable intelligence that 1,429 people died in the chemical onslaught, where are the bodies?"

Ye added that a limited strike from the US will by no means stop the use of chemical weapons in Syria, if the allegation is true.

The strike is also meaningless in terms of ending the rule of the Syrian government, he said.

"Besides, Barack Obama is unlikely to get UN authorization or support from most other countries," Ye said.

"Actually, Obama does not want to launch the strike. However, the hawkish stance of interest groups in Washington and some senior US diplomats, including Secretary of State John Kerry, have exerted much pressure on him."

Yin Gang, also an expert on Middle East studies at the Chinese Academy of Social Sciences, said Obama is not "seeking" approval from Congress.

"He will only have to launch the attack if Congress approves," Yin said, adding that the US Congress cannot limit the right of the president to launch such an attack.

A war with Syria would drag Washington into further confrontations with various sections of Islam and heighten tensions in the Middle East — a situation Washington will not want to see, Yin said.

"That is why Obama just wants a limited strike, if he has to launch one."

Jon Alterman, director of the Middle East Program at the Center for Strategic and International Studies, told Reuters that Obama's decision "to get Congress on board when he hasn't had a huge amount of success working with Congress strikes me as a gamble".

A failed vote, he said, "could shadow the rest of the administration".

Mo Jingxi contributed to this story.