The five-year-old boy, identified as Nikita Konkin by the press, was clearly stunned by the kiss and speculation over Putin's motivation has run wild in the week since it happened.
Curious Internet users propelled the issue to the top of a list of questions put to Putin in an interactive Web cast. ( Watch Putin and the boy -- :45)
"People came up and I began talking to them, among them this little boy. He seemed to me very independent, sure of himself and at the same time defenseless so to speak, an innocent boy and a very nice little boy," Putin told the Web cast.
"I tell you honestly, I just wanted to touch him like a kitten and that desire of mine ended in that act."
The Izvestia daily, which tracked down Nikita, discovered that he had refused to wash after that kiss.
"I just liked him and he liked me very much. I want to be president myself," the five-year-old told the paper.
Putin was shown by state television chatting to graduates of military academies before he took a walk through one of the Kremlin's courtyards, often full of tourists.
He stopped and spoke to Nikita who turned away shyly. "What is your name?" Putin asked, kneeling down in front of the fair-haired boy and holding him by the waist.
"Nikita," the clearly shocked boy answered, looking from side to side.
Putin then lifted the boy's shirt and kissed him on his stomach. The Russian president then patted the boy on the head and walked off through a crowd of astonished tourists.