This zone would stretch up to 25 miles into Syria, and would be enforced by warplanes flying inside Jordan and armed with long-distance air-to-air missiles, the Wall Street Journal reported, citing unnamed US officials.
Military experts have long warned that a no-fly zone would require Western jets to destroy the regime's relatively good air defences.
But US planners believe this no-fly zone could be imposed in about a month without having to destroy the Syrian antiaircraft batteries.
It could also be imposed without a UN Security Council resolution because US warplanes would not regularly enter Syrian airspace, and the US military would not be holding Syrian territory.
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"Unless you have a good buffer zone inside Syria, you risk too much," an unnamed US official briefed on the military proposal told the Journal.
This limited no-fly zone would cost about $50 million a day, far less than a Syria-wide no-fly zone. US officials hope that Washington's allies could help cover the cost.
The US planes would fly from Jordan -- where US Patriot missiles and F-16 jet fighters have already been deployed -- and from navy ships in the Mediterranean and the Red Sea, the Journal reported.
"We can establish a no-fly zone without sending a single manned airplane over Syria... And we can change this equation on the battlefield," McCain said yesterday.