Did a Russian military convoy enter Ukraine?

The U.S. is investigating reports that the Ukrainian military destroyed a convoy of Russian military vehicles that crossed into its territory, the White House said Friday.

While the administration cannot yet independently confirm Kiev's clams that it attacked Russian vehicles that had crossed the border, national security council spokesperson Caitlin Hayden expressed concern over "repeated Russian and Russian-supported incursions into Ukraine."

"Russia has no right to send vehicles, persons, or cargo of any kind into Ukraine, under any pretext, without the Government of Ukraine’s permission," Hayden said in a statement. "The escalation in Russian activity designed to destabilize Ukraine in recent weeks is extremely dangerous and provocative."

Ukrainian President Petro Poroshenko told British Prime Minister David Cameron earlier Friday that Ukrainian forces had destroyed "the majority" of a group of Russian military armored vehicles that had entered Ukrainian territory, according to a statement on his website.

Ukrainian Defense Ministry spokesman Leonid Matyukhin said the vehicles had been painted white so as to appear like peacekeeping vehicles in an interview with Bloomberg News.  NATO chief Anders Fogh Rasmussen said earlier Friday that "a Russian incursion" had occurred overnight, telling reporters the activity was "a clear demonstration of continued Russian involvement in the destabilization of eastern Ukraine." 

But Russia's defense ministry denied that there was any such convoy, according to the BBC.

The reports came as Russia separately moved hundreds of trucks reportedly carrying humanitarian aid across the Ukrainian border to be inspected by the International Committee of the Red Cross.

Ukrainian and Western leaders have expressed skepticism about the aid shipments, saying they were concerned it could be a bid to move Russian military supplies or troops into Ukraine.

In a phone call earlier Friday with Defense Secretary Chuck HagelCharles (Chuck) Timothy HagelPentagon documents hundreds of serious misconduct cases against top brass Obama defense sec: Trump's treatment of Gold Star families 'sickens' me The Hill's 12:30 Report MORE, the head of Russia's defense ministry "guaranteed" that no military personnel were traveling with the convoy, according to the Pentagon. Russian Defense Minister Sergey Shoygu also said Moscow would comply with the international inspections of that cargo.

The White House says Russia has continued to supply separatists fighters with tanks, armored vehicles, artillery, and multiple rocket launchers, even after the downing of a Malaysian commercial plane earlier this summer. The U.S. has also accused Russia of firing rockets from its own territory into Ukraine.

"Yesterday, President Putin pledged to “do everything in (Russia’s) power” to end the conflict in Ukraine.  He can start by ending Russian firing into Ukraine; stopping its supply of weapons, support and cash to separatists; and closing the border to militants, including by facilitating an effective border monitoring mission," Hayden said.

"The continued Russian military intervention into Ukraine is entirely at odds with legitimate efforts to provide humanitarian assistance and negotiate a peaceful resolution to the overall crisis," she added.