MOSCOW — A gift horse or a Trojan horse?

That about summed up the latest, almost farcical encounter between Moscow and Kiev, as a mammoth convoy of some 260 trucks thundered across Russia on Tuesday bearing thousands of tons of humanitarian aid for the people of the besieged Ukrainian city of Luhansk.

The Kremlin has insisted that it is interested only in relieving the suffering of civilians and has called for the supplies to be delivered speedily under the auspices of the International Committee of the Red Cross. But Ukraine, suspecting that the convoy is more a threat than a sincere offer of help — perhaps an attempt to infiltrate Russian forces into the country under the guise of a humanitarian mission — said on Tuesday that the trucks would be barred at the border.

The tumult seemed the latest in a series of international episodes involving President Vladimir V. Putin of Russia casting himself as a savior while the objects of his largess try to find a way to avoid taking it. Even the Red Cross did not seem that eager to become embroiled in the situation, with its spokesman slow to return telephone calls or saying simply that the technical details were incomplete.

“There is a lot of suspicion and a lot of mistrust,” said Konstantin von Eggert, a Moscow-based political analyst. “Under these circumstances, it is going to be treated like a wolf in sheep’s clothing.”