A Syrian member of parliament on Saturday blasted the United States' decision to send troops into Syria as an “act of aggression”.

Speaking to The Associated Press (AP), the lawmaker, Sharif Shehadeh, said the American troops will have no effect on the ground, but Washington wants to say it is present in Syria.

"What has happened to make America realize, after five years, that it should send between 30 and 50 military advisers?" asked Shehadeh, referring to the start of the country's civil war in March 2011 that has since killed more than 250,000 people.

"When America sends ground forces into Syrian territories without an agreement with the Syrian government it becomes an intervention and aggression," he stated. "Will America allow Russian ground forces to go into America without an agreement? I think the answer is no."

On Friday, President Barack Obama okayed a deployment of "fewer than 50" special operations forces in the north of Syria, in a bid to strengthen forces fighting the Islamic State (ISIS) group.

Secretary of State John Kerry on Saturday refused to rule out more American commandos being sent to Syria beyond the 50 announced Friday.

Speaking in the Kyrgyz capital during a tour of Central Asia, Kerry said he fully supported Obama's decision to put troops on the ground in Syria - which comes just weeks after Russia's surprising deployment in the war torn state.

Asked whether he could rule out more troops being assigned to the mission, he said, "I can't predict what the future will bring when our policy is to destroy Daesh, to fight back against this evil. But I do think the president has made a judgment that I completely advocated for and concur in."

Meanwhile, State Department spokesperson John Kirby was put in the hot seat on Friday, when Reuters reporter Arshad Mohammed asked him at a press briefing about Obama's decision and whether he broke his word about not putting American boots on the ground in Syria.

Kirby claimed that he "didn't know" whether Obama had ruled out putting boots on the ground in Syria - even though Obama openly announced as far back as 2013 that he would not do so.

When pressed, Kirby said, "I’ll defer to my colleagues at the White House to speak to presidential policy here, I’m not aware that there was a policy about putting U.S. boots on the ground in Syria in any capacity whatsoever."