At least 134 Russian vehicles have entered eastern Ukraine, claiming to be a convoy bringing aid to a war-torn part of the country.

But Ukraine said the border crossing violated an agreement between the two countries and said that Russia has invaded the country, CNN reported.

"We call this a direct invasion for the first time under cynical cover of the Red Cross," said Valentyn Nalyvaychenko, head of Ukraine's security service.

Ukraine previously had said that the Russian convoy could come into the country if the International Committee of the Red Cross would be with them. Customs officials allowed 34 trucks to cross the border, thinking the Red Cross was part of the group.

But Red Cross officials said the organization had left the convoy because of security concerns about the fighting between pro-Russian forces and the Ukrainian military.

Ukraine believes that Russia has been using the aid convoy as a guise to get into the country, and international organizations seem to agree.

"It can only deepen the crisis in the region, which Russia itself has created and has continued to fuel," NATO Secretary General Anders Fogh Rasmussen said, labeling the Russian caravan a "so-called" humanitarian convoy. "The disregard of international humanitarian principles raises further questions about whether the true purpose of the aid convoy is to support civilians or to resupply armed separatists."

The latest reports claim that Russia has somewhere around 18,000 combat-ready troops stationed at its border with Ukraine, which is significantly more soldiers than had been estimated. A U.S. Army official said the troops are in a "fully combat-capable posture."

"They are definitely more overt, aggressive and out in the open," the official said. "They aren't even hiding it."

Rear Adm. John Kirby, Pentagon spokesman, said that the Russian convoy in Ukraine is an unauthorized entry and that Russia must withdraw immediately, according to The New York Times. He went on to say that no Russian troops should enter Ukraine claiming humanitarian aid.