Pentagon press secretary John Kirby said Russian forces are "broadening their target sets" after rockets hit a Ukrainian military base near the Polish border overnight.
"Look, this is the third now military facility or airfield that the Russians had struck in western Ukraine in just the last couple of days," Kirby told ABC "This Week" co-anchor Martha Raddatz, on Sunday. "So, clearly, at least from an airstrike perspective, they're broadening their target sets."
The Yavoriv International Center for Peacekeeping and Security, located about 10 miles from Poland and an hour west of Lviv, sustained damage from the airstrike. Lviv Gov. Maksym Kozytskiy said at least 35 people were killed and another 134 injured during the attack on the Ukrainian military training base. Kirby confirmed no Americans were present.
Raddatz followed up, citing Ukraine's defense minister calling the strike "a terror attack near the NATO border" and "saying action must be taken to stop this, close the sky."
"Could a no-fly zone have stopped this?" she asked.
"No, I don't think so," Kirby responded. "Look, I mean, no-fly zone has a nice air policing kind of sound to it. But I participated in one as a young officer on an aircraft carrier way back in the early '90s. It is combat. You have to be willing to shoot and to be shot at." He added that U.S. troops in Ukraine "leads to war with Russia."
MORE: Pentagon again rejects Poland's plan to make US provide Ukraine fighter jetsRaddatz asked, "If those attacks on military supply centers cross into Poland -- and I know that is a fear of the United States and the NATO allies -- what changes? Kamala Harris just reaffirmed the pledge -- the Article 5 pledge -- to defend NATO members. If they strike in Poland, what happens?"
"We take our Article 5 commitment very seriously and the vice president was pretty firm about that on her recent visit, so has been [Defense] Secretary [Lloyd] Austin," Kirby answered. "An armed attack against one is considered an armed attack against all. That is why, Martha, we continue to flow and to move and to reposition forces and capabilities along NATO's eastern flank to make sure that we can defend every inch of NATO territory if we need to."
"Now, there's no reason we should need to because there's no reason that there should be war in Ukraine as it is, and we've made it very clear to Russia that NATO territory will be defended not just by the United States, but by our allies," Kirby later added.
"But this was just 10 miles from that border," Raddatz pressed again, saying, "I just crossed that border the other day. Doesn't this change the way you look at things? They're getting closer and closer to our NATO allies."
"I can tell you that we have been consistently concerned about NATO's eastern flank and that airspace and, of course, that ground space on that flank of NATO. And we continue to look for ways to bolster the defenses of our NATO allies," Kirby said.
The U.N. Security Council scheduled a meeting Friday at Russia's request to discuss the unfounded Russian claim that the U.S. is working with Ukraine on developing biochemical weapons, an allegation the Biden administration has vehemently denied.
MORE: Russia escalates false chemical weapons claims about US, Ukraine by bringing them to UN"It is of the Russian playbook that that which they accuse you of they're planning to do now," Kirby said. "Now, again, we haven't seen anything into it indicates some sort of imminent chemical or biological attack right now, but we're watching this very, very closely."
On Friday, President Joe Biden said Russia "would pay a severe price" if any biochemical weapons are utilized during the unprovoked invasion of Ukraine.
MORE: Biden warns Russia will pay 'severe price' if it deploys chemical weaponsBut as Ukrainian leaders plead for a no-fly zone over their country, Markian Lubkivskyi, an adviser to the Ukrainian defense minister, said during an earlier "This Week" interview that Ukraine was "still waiting for the weapons, for the aircraft, for the anti-air systems to protect Ukrainians from the air."
Kirby, however, said assistance would "continue to flow" to the country.
"The kinds of things we know they most need, the kinds of things that they're using so well, we're going to continue to help get them into their hands. And we know that it is working, that they are receiving them and they are using them."
"I mean they have impressed everybody around the world and certainly they have impressed the Russians who have been increasingly flummoxed and frustrated about their lack of progress because of this Ukrainian resistance," he added.