NATO has a "responsibility to ensure that the conflict does not spread beyond Ukraine," said Secretary General Jens Stoltenberg.
Speaking during a joint press conference in Riga with the Latvian President Egils Levits on Tuesday, Stoltenberg remarked that the "suffering we now see in Ukraine is horrific."
We have a responsibility to ensure the conflict does not escalate and spread beyond Ukraine. That would be even more dangerous, destructive, and even more deadly. The situation could spiral out of control," Stoltenberg said.
In response to the situation and to "make sure there is no room for miscalculation in Moscow" NATO has "significantly strengthened" its presence in the eastern part of the alliance, Stoltenberg added.
"We have 130 jets at high alert. Over 200 ships from the high north to the Mediterranean, and 1000s of additional troops in the region," the NATO chief continued.
NATO will "protect and defend every inch of allied territory," Stoltenberg said.
So far, NATO has refused to get directly involved in the conflict -- including setting up a no-fly zone -- beyond supporting Ukraine's resistance to Russia's invasion.
CNN's Luke McGee contributed reporting to this post.