Kiev has been making the same accusation since March.
As new measures against the EU and the U.S. have been imposed by Moscow, NATO now claims that Russia could be planning an invasion on Ukraine.
“We're not going to guess what's on Russia's mind, but we can see what Russia is doing on the ground – and that is of great concern,” said NATO spokeswoman Oana Lungescu.
The accusations come after Russia announced military drills on it's border with Ukraine, and proposed yesterday in an emergency Security Council meeting to send peacekeeping forces.
NATO's claim is based on Russian protection of it's border with Ukraine.
NATO is concerned that Moscow could use "the pretext of a humanitarian or peace-keeping mission as an excuse to send troops into Eastern Ukraine," she said.
But claims of Russia invading Ukraine are not new. Since March, Ukrainian officials and local media outlets have been announcing an alleged Russian invasion.
For example, earlier in March, the pro-Kiev newspaper Kyiv Post reported on the Ukrainian government's fears of a full-scale invasion.
Ukraine's deputy foreign minister Danylo Lubkivsky told reporters at the United Nations on April 25 that they feared an imminent Russian invasion. "We have the information we are in danger," he stated.
Andrii Deshchytsia, foreign minister, said in May that Russia had infiltrated Ukraine's eastern areas and was planning to invade the country.
NATO's declarations come amid Moscow's announcement of new countermeasures against U.S. and EU, which imposed new sanctions on Russia last week.