The incident occurred Friday morning, when 130 KamAZ trucks that are part of a 270-vehicle Russian aid convoy destined for eastern Ukraine bypassed inspection from Ukrainian officials with the help of a Russian force blockade, and entered Ukraine without escort by International Committee of the Red Cross personnel.
NATO condemned Russia's actions as "a blatant breach of Russia's international commitments... and a further violation of Ukraine's sovereignty by Russia."
"These developments are even more worrying as they coincide with a major escalation in Russian military involvement in eastern Ukraine since mid-August, including the use of Russian forces."
Such incidents have included Russian artillery support against Ukrainian armed forces, the transfer of advanced weaponry across the border to pro-Russian separatists, and a build-up of Russian ground and air forces in Ukraine's vicinity.
Rasmussen noted that Russia's latest action "can only deepen the crisis in the region, which Russia itself has created and has continued to fuel."
When the Russian aid convoy departed Moscow on August 12 there was suspicion about the cargo's contents and Russia's intentions because the 270-vehicle convoy was dispatched without necessary approval from the Red Cross or permission from the Ukrainian government. The convoy has been delayed while agreements were worked out concerning cargo verification and delivery procedures.
Friday's forced entry into Ukraine, Rasmussen said, "raises further questions about whether the true purpose of the aid convoy is to support civilians or to resupply armed separatists."
The Ukrainian government declared Friday's incident "a direct invasion for the first time under the cynical cover of the Red Cross."