The Kremlin made the details of the visit public a day later, on Wednesday. It did not say whether the Syrian leader was still in Moscow or had returned home.
Syria operation shows Russia can counter 'any threats': Putin
The visit is believed to be Assad's first foreign trip since the outbreak of the Syrian crisis in 2011 and comes three weeks after Russia launched a campaign of air strikes against militants in Syria on Sept. 30.
"First of all I wanted to express my huge gratitude to the whole leadership of the Russian Federation for the help they are giving Syria," Assad told Putin, according to a Kremlin transcript.
"If it was not for your actions and your decisions the terrorism which is spreading in the region would have swallowed up a much greater area and spread over an even greater area."
45 killed in Russian air strikes in Syria's Latakia: monitor
Putin hailed the Syrian people for standing up to the militants "almost on their own," saying the Syrian army had notched up serious battle field success in recent times.
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