U.S. warns of Russian build-up on Ukraine border

• NEW: U.S. calls Russian convoy in Ukraine an “unauthorized entry”
• Russia says its aid convoy is moving into eastern Ukraine, bound for Luhansk
• International Committee of the Red Cross says it is not accompanying the convoy
• Russian Foreign Ministry accuses Ukraine of inventing excuses to stop convoy

Kiev, Ukraine (CNN) — What Russia calls a humanitarian convoy into eastern Ukraine was criticized by NATO, the United States and Ukraine itself on Friday as a guise for violating its neighbor’s sovereignty.

Russia diverted 34 trucks from an aid convoy into eastern Ukraine after Russian and Ukrainian customs officials cleared them under the assumption that the International Committee of the Red Cross would be with them, the Ukrainian military said.

But the Red Cross said it was no longer with the convoy because of the “volatile security situation,” a reference to fighting between pro-Russian rebels and Ukrainian forces. This was a violation of the deal between the two countries that any humanitarian convoy must be monitored by the Red Cross.

In total, at least 134 Russian vehicles in the aid convoy had entered Ukraine as of 2:20 p.m., according to the Organization for Security and Co-operation in Europe, which has an observer mission at the checkpoint the convoy is passing through.

The unaccompanied trucks effectively constitute a Russian invasion of Ukraine, said Valentyn Nalyvaychenko, the head of Ukraine’s security service.

“We call this a direct invasion for the first time under cynical cover of the Red Cross,” Nalyvaychenko said Friday.

NATO Secretary General Anders Fogh Rasmussen referred to the movement as a “so-called humanitarian convoy.”

The first trucks of a Russian aid convoy roll on the main road to Luhansk in eastern Ukraine on Friday, August 22. The head of Ukraine’s security service called the convoy a “direct invasion” under the guise of humanitarian aid since it entered the country without Red Cross monitors. Ukrainian government forces have been battling pro-Russian rebels near Ukraine’s eastern border with Russia. The fighting has left more than 2,000 people dead since mid-April, according to estimates from U.N. officials.A pro-Russian rebel holds shrapnel from a rocket after shelling in Donetsk, Ukraine, on August 22.Residents sit in a makeshift bomb shelter during a shelling in Makiyivka, Ukraine, on Wednesday, August 20.Dogs play together as a Russian convoy carrying aid supplies stops at a border control point with Ukraine, in the Russian town of Donetsk, in the Rostov-on-Don region on August 20.Ukrainian forces take their position not far from Luhansk, Ukraine, on August 20. Ukrainian troops made a significant push into rebel-held territory in eastern Ukraine, claiming control over a large part of Luhansk and encircling the largest rebel-held city, Donetsk, in fighting that has left at least 43 dead. Clouds of smoke are on the horizon as Ukrainian forces and pro-Russian rebels clash in Yasynuvata, a suburb of Donetsk, Ukraine, on Tuesday, August 19. An Ukrainian helicopter flies near Kramatorsk, Ukraine, on August 19.Ukrainian soldiers load a missile during fighting with pro-Russian rebels Monday, August 18, near Luhansk, Ukraine.Boys play at a refugee camp, set up by the Russian Emergencies Ministry, near the Russian-Ukrainian border on August 18.Ukrainian soldiers carry weapons at a checkpoint near Debaltseve, Ukraine, on Saturday, August 16.Pro-Russian rebels greet each other as they pass near Krasnodon, Ukraine, on August 16.A fireman tries to extinguish a fire after shelling in Donetsk on August 16.Ukrainian border guards patrol near Novoazovsk, Ukraine, on Friday, August 15.Trucks of a Russian humanitarian convoy are parked in a field outside the town of Kamensk-Shakhtinsky, in the Rostov region of Russia about 20 miles from the Ukraine border, on August 15. Ukrainian officials were preparing to inspect the convoy, which was bound for the conflict-torn east.A truck driver from the convoy jumps out of a trailer on August 15. The Ukrainian government had expressed fears that the convoy was a large-scale effort to smuggle supplies or troops to pro-Russian rebels.A tank belonging to pro-Russian rebels moves along a street in Donetsk on August 15.A Ukrainian soldier walks past a line of self-propelled guns as a column of military vehicles prepares to head to the front line near Illovaisk, Ukraine, on Thursday, August 14.A Ukrainian soldier prepares a mortar at a position near Illovaisk on August 14. A man inspects damage at his house after a shelling in Donetsk on August 14. A convoy of trucks, which Moscow said was carrying relief goods for war-weary civilians, moves from Voronezh, Russia, toward Rostov-on-Don, Russia, on August 14.Pro-Russian rebels on the outskirts of Donetsk stand at a checkpoint near a bullet-riddled bus on Wednesday, August 13.A pro-Russian rebel inspects damage after shelling in Donetsk on Thursday, August 7.Smoke billows from a Ukrainian fighter jet crash near the village of Zhdanivka, Ukraine, on August 7. Residents of eastern Ukraine cry in a hospital basement being used as a bomb shelter August 7 in Donetsk.Ordnance from a Ukrainian rocket launcher shoots toward a pro-Russian militant position in the Donetsk region on August 7.Relatives of Ukrainian military member Kyril Andrienko, who died in combat in eastern Ukraine, gather during his funeral in Lviv, Ukraine, on August 7.Refugees from southeastern Ukraine wait at a refugee camp in Donetsk on Wednesday, August 6.A pro-Russian rebel adjusts his weapon in Donetsk on August 6.Men walk past a bomb crater in Donetsk on August 6.A man steps out of his car as Ukrainian soldiers inspect the vehicle at a checkpoint in Debaltseve on August 6.Ukrainian servicemen sit on a bus near Slovyansk, Ukraine, on Tuesday, August 5.A pro-Russian separatist guards a road as Australian, Malaysian and Dutch investigators prepare to examine the crash site of Malaysia Airlines Flight 17 near the village of Rossipne, Ukraine, on August 5. U.S. and Ukrainian officials allege that a Russian-made missile shot down the plane from rebel-held territory, killing all 298 people on board. Russia and the rebel fighters deny involvement.Rescue workers carry the body of a woman who was killed during a bomb shelling in Donetsk on August 5.A boy stands in a hallway of a refugee hostel run by pro-Russian rebels in Donetsk on Monday, August 4.Ukrainian servicemen from the Donbass volunteer battalion clean their guns Sunday, August 3, in Popasna, Ukraine.Ukrainian soldiers fire shells toward rebel positions near Pervomaysk, Ukraine, on Saturday, August 2.Ukrainian troops patrol near the village of Novoselovka on Thursday, July 31.A woman says goodbye to her mother as she flees her home in Shakhtersk, Ukraine, on Tuesday, July 29. See more photos of the crisis from earlier this yearCrisis in UkraineArmy: Civilian convoy attacked in UkraineUkrainian refugees flee to Russia

“It can only deepen the crisis in the region, which Russia itself has created and has continued to fuel,” he said in a statement. “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 presence of Russian vehicles in Ukraine is an “unauthorized entry,” and the personnel and vehicles must be removed immediately, Pentagon spokesman Rear Adm. John Kirby said Friday. No Russian personnel should enter Ukraine under the guise of a humanitarian convoy, Kirby said.

Russia has up to 18,000 “combat-ready” troops on its border with Ukraine on Friday, a significant increase from previous public estimates by the Pentagon, according to a U.S. defense official with direct access to the latest information.

The official described the units as being in a “fully combat-capable offensive posture.”

A second U.S. official said that many of the units were positioned at “crossroads and towns” 2 to 10 miles from the border.

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

The second official said the United States has believed for weeks that some Russian troops have crossed the border as part of the convoys of military gear and weapons moving from Russia into Ukraine. Of particular concern is the apparent transport of long-range and advanced systems including at least two SA-22 surface to air missile system and a number of pieces of longer-range artillery.

Troublesome convoy

The news was the latest flashpoint in tensions between Moscow and Kiev, which for months has accused Russia of sending supplies into Ukraine to support pro-Russian rebels in Ukraine’s east.

Ukraine, as of now, doesn’t plan to use force against the convoy, though Kiev suspects that the trucks’ supplies will be given to rebels, Nalyvaychenko said.

Meanwhile, another 90 vehicles are headed toward the Ukrainian border, according to Col. Andriy Lysenko, spokesman for Ukraine’s National Defense and Security Council. Ukrainian border guards, customs officers and Red Cross representatives have not been given access to that group, Lysenko said.

He said that the Ukrainian side had proposed talks with Russia over the humanitarian aid but that Moscow had refused.

The trucks were part of a larger convoy that left the Moscow area last week, with Russia insisting that it be allowed to send aid to civilians — many of them Russian speakers — affected by the months of fighting in eastern Ukraine. Aid groups say the battles have left thousands without access to water, electricity and proper medical aid.

Ukraine, concerned that Russia might try to smuggle military supplies, stalled the trucks for days on the Russian side of the border.

But Ukrainian officials acknowledged Sunday that the convoy of more than 260 Russian vehicles was, in fact, carrying humanitarian aid.

Red Cross monitors were supposed to accompany the initial 34 vehicles but decided not to do so because they did not get the security guarantees they needed, the agency said.

Russia’s Foreign Ministry said the first group of trucks was headed toward Luhansk, one of two Ukrainian regions at the center of the conflict.

Russian state news agency Itar-Tass said the initial convoy carried food and essential items for people in the region.

Ukraine’s National Security and Defense Council said Friday that the customs service had granted access for 34 vehicles, 34 people and 268,020 kilograms of Russian humanitarian aid.

Russia says Ukraine used pretexts to hold up convoy

In a statement Friday, Russia’s Foreign Ministry accused Ukraine of using pretexts in the days since to hold up the movement of the convoy while escalating its attacks on pro-Russia rebels in the Donetsk and Luhansk regions.

The ministry claimed that Ukrainian leaders were deliberately delaying the delivery of the humanitarian aid until there was no one left to deliver it to.

It said that it was ready for Red Cross staffers to accompany the Russian convoy and help with the distribution of aid.

Still, Ukraine’s government has suspicions. Nalyvaychenko said he believes the neither the trucks nor the drivers are civilian. The drivers, he said, received Russian passports only two weeks ago — days before Moscow started sending the convoy to the border.

The ongoing fighting — sparked last year by a political crisis over whether Ukraine would seek closer ties with Europe or Russia — has left more than 2,000 people dead and nearly 5,000 wounded in eastern Ukraine since mid-April, according to estimates from U.N. officials.

Four Ukrainian soldiers have been killed over the past 24 hours, Ukraine’s National Security and Defense Council said Friday.