The network cited unnamed US defense officials as saying "a good number" of the unmanned military and intelligence planes were operating in Syrian skies.
They insist that the drones are not collecting information to be used in future military intervention:
"Rather, the Obama administration hopes to use the overhead visual evidence and intercepts of Syrian government and military communications in an effort to 'make the case for a widespread international response,' the officials told [NBC correspondent Jim] Miklaszewski."
The report added that government and Pentagon officials had discussed the possibility of "humanitarian missions" in Syria, but were reluctant to endanger their staff or inadvertently draw the US into a military role.
The report came as China's special envoy to Syria, Vice Foreign Minister Zhai Jun, called on the international community to respect Syria's "sovereignty, unity, independence and territorial integrity," the Al Arabiya news site reported. China, alongside Russia, has twice vetoed a UN Security Council resolution demanding an end to the crackdown.
"The position of China is to call on the government, the opposition and the rebels to halt acts of violence immediately," Al Jazeera quoted Zhai as telling Syrian TV. "We hope that the referendum on a new constitution as well as the forthcoming parliamentary elections pass off calmly."
Zhai described China as a "friend of Syria," according to Chinese news agency Xinhua, but stressed that Beijing held "an objective and just stance on the issue of Syria, taking the fundamental interests of the Syrian people into consideration."
Zhai arrived in Damascus yesterday for two days of talks with President Bashar al-Assad and "various political factions," Xinhua said.
According to the BBC, following their meeting President Assad said: "What Syria is facing is fundamentally an effort to divide it and affect its geopolitical place and historic role in the region."
Meanwhile there were reports of continuing attacks on protesters, including at a funeral procession in the capital. Security forces fired live rounds and tear gas at thousands of people marching in a procession-cum-rally Saturday morning, activists told the Associated Press, leaving several people reported injured.
And on Friday, government forces were reported to have renewed their rocket and artillery attacks on Homs, killing 56 people.