Almost as soon as the trucks began moving, accusations and warnings from both sides over the true nature of what Moscow calls an aid convoy, but Ukraine believes is a trojan horse being used to disguise an invasion of its territory.

Ukraine government spokesman Valentyn Nalivaychenko says he's in no doubt about Russia;'s intentions.

(SOUNDBITE) UKRAINIAN SECURITY SERVICE (SBU) CHIEF, VALENTYN NALIVAYCHENKO, SAYING:

"It's a direct invasion with the cynical use of Red Cross. These are military vehicles. These are servicemen with fake documents.

But Moscow maintains that the trucks are transporting much-needed humanitarian aid to Russian speaking residents of Ukraine cities beseiged by government forces.

Russian Foreign Ministry spokesman Alexander Lukashevich is warning Kiev against any interference.

SOUNDBITE) RUSSIAN FOREIGN MINISTRY SPOKESMAN, ALEXANDER LUKASHEVICH, SAYING:

"We warn against any attempts to disrupt the purely humanitarian missi