AMNA NAWAZ: Today, over two NATO countries, jets raced across the skies to shoot down drones.

It's the latest example of at least a half-a-dozen drone incursions in the Baltics just in the last week.

The nations along NATO's Eastern flank have long been on the front line against Russian aggression, but now they're in the firing line between Ukraine's long-range drones and targets in Northwest Russia.

Nick Schifrin talks to Latvia's foreign minister and reports on NATO's efforts to defend itself against a growing drone threat.

NICK SCHIFRIN: Today in Latvia, fighter jets scramble to intercept a drone for at least the third time this month.

But this drone and the one that hit this Latvian oil facility earlier this month and these drone shards shot down by a NATO jet over an Estonian field were Ukrainian, not Russian.

And this week in Lithuania, suspected Ukrainian drones forced government leaders to shelter in a bunker beneath Parliament, the first time that's happened in a NATO capital since Russia launched its full-scale invasion of Ukraine more than four years ago.

BAIBA BRAZE, Latvian Minister of Foreign Affairs: Russia is, of course, attacking Ukraine, and Ukraine is doing itself-defense.

So it's flying drones into Russia, and then Russian electronic warfare, of course, misdirects them.

And then sometimes they fly into our airspace.

NICK SCHIFRIN: Baiba Braze is Latvia's foreign minister.

We spoke while she attended a NATO summit in Sweden.

She and other Baltic leaders say the Ukrainian drones were forced off course by Russia.

But other European officials have wondered whether the Ukrainian drones were autonomous and chose their own incorrect targets.

BAIBA BRAZE: The two drones that were examined were found not to be those type of drones, so I won't release any further information, as it's classified.

Let's remember, if it was not for Russia's wars -- war against Ukraine, these incidents wouldn't happen.

So it's Russia's fault.

NICK SCHIFRIN: Russia accuses Latvia specifically of allowing Ukraine to use your airspace for drone attacks in Russia and even to launch attacks.

Is that true?

BAIBA BRAZE: Russia has been lying for whatever -- I remember, since I remember myself, there have been lies from the USSR, from Russia.

So don't believe what Russia says, especially the official representatives.

And the truth is that, of course, we are not providing anything to Ukraine's attacks.

We are not providing airspace.

We are not providing our ground.

We are not providing anything.

NICK SCHIFRIN: Is Ukraine being careful in its targeting and its -- and the paths that it is sending these drones on?

BAIBA BRAZE: We have been in touch with Ukrainian officials with very clear message that our space is out of limits.

And they know that, so they haven't violated anything.

NICK SCHIFRIN: Ukraine's targets are in Russia along the Baltic Sea or next to the Baltic states, all three of which are former Soviet republics, including the largest ports where Russia exports oil, hoping to disrupt the Kremlin's most important source of income.

BAIBA BRAZE: Russia is trying to hide its inability to achieve its military objectives and the fact that Ukraine has these successful technologies and Russia cannot defend against them.

NICK SCHIFRIN: But Russian drones also pose a threat to NATO, and NATO is struggling to keep up.

NARRATOR: The nature of warfare is changing.

NICK SCHIFRIN: NATO does not yet have unified counterdrone capabilities in the eastern flank, and so is launching new initiatives along the Russian border.

NARRATOR: With it, we fight as one.

NICK SCHIFRIN: Today, NATO still has to scramble jets and use expensive missiles to target cheap Russian drones.

And it's difficult to detect different types of Russian drones as they cross the border.

BAIBA BRAZE: The truth is, none of NATO's countries has the battlefield like Ukraine has.

And so we have to make sure that our transformation is faster, that it's massive, that we have all what is necessary to defend, but also to be ready.

So there are big lessons still to be learned for all of NATO allies.

NICK SCHIFRIN: The Baltics are on the front lines, and they conduct exercises in case of Russian invasion and have built border defenses that didn't exist before Russia's full-scale invasion of Ukraine.

They have also realized the Ukraine war has become a drone battle and the best source for lessons learned.

BAIBA BRAZE: Ukraine has the most advanced data, most advanced technology, because it's fighting for its existence.

And it has been great at innovation, and it has been great at the upgrades within few weeks and doing everything that needs to be done in the situation of war.

So, none of NATO states is in that position.

However, we are indeed working with the Ukrainians, and we are carefully following also what Russia is doing, because Russia is also learning.

NICK SCHIFRIN: And so it's a race of learning and innovation of how best to defend NATO, even when it's inadvertently from a partner.

For the "PBS News Hour," I'm Nick Schifrin.