After recent drone incursions into Polish and Romanian airspace, NATO has launched Operation Eastern Sentry to strengthen its eastern flank. How serious is the threat from Russia? And can NATO deter future provocations?

Drone incidents have been making headlines across Europe for over a week now.

On the night of September 9/10, an unprecedented wave of Russian drones entered Polish airspace. Up to 19 unmanned aerial vehicles were identified, a handful of which were shot down.

Just days later, Russian drones crossed into the territory of Romania, another NATO member.

On Monday, Polish authorities took down a drone that was flying over government buildings in Warsaw and reportedly detained a Belarusian and a Ukrainian suspect.

No one was injured in these incidents, and Russia denies that the incursions were deliberate. Nevertheless, NATO has responded by launching a new mission to safeguard the airspace on its eastern flank.

Dubbed Eastern Sentry, the "multi-domain activity" will involve the strengthening of both ground bases and air defenses and "continue for an undisclosed amount of time," the defense alliance announced in an official statement on September 12.

With this new operation, NATO wants to send a clear message both to its eastern member states and to Russia.

The UK and Denmark have, among others, pledged support for the initiative. Germany has doubled the number of combat aircraft dedicated to air defense in Poland from two to four, and France has deployed Rafale fighter jets.

While jets and air-to-air missiles have successfully been deployed against drones, they are anything but cost-effective.

"The kind of drone we're seeing in Ukraine costs between €10,000 and €30,000 [$11,800 to $35,400] a piece. If you're firing million-dollar missiles at them, you're going to run out of those very fast," Chris Kremidas-Courtney, a defense expert at the Brussels-based think tank European Policy Centre (EPC) told DW. "We're using a sledgehammer on a thumbtack."

Kremidas-Courtney explained that European NATO members should instead invest in more efficient modern defense technology that can stop drones at a fraction of the cost, giving the Swedish-built Nimbrix anti-drone missile system as an example. Otherwise, they said, Europe would be stuck with a problematic "cost asymmetry."

The Baltic states, which regularly deal with Russian incursions into their airspace, Poland and Finland have been asking for an increase in coordinated drone defense for several years.

This concept has often been referred to as a "drone wall" -- a term picked up by European Commission President Ursula von der Leyen in her latest State of the Union speech.

Ukrainian know-how is set to play a key role in building this figurative wall, with the Commission announcing a €6-billion joint drone production project.

"We need to learn from the Ukrainians," Ian Bond, deputy director of the Brussels-based think tank Centre for European Reform (CER) told DW. "They have a pretty high success rate in bringing down Russian drones, and if they have the technology to do it, we need to acquire it and copy it."

One of the key challenges for NATO will be to implement new drone defense technology at scale, Admiral Rob Bauer, former chair of NATO's Military Committee, said in an interview with DW.

Bauer went on to say that in addition to investing in new hardware, Europe needs to adopt a different mentality toward Russia: "We need to inform our public, and people need to accept there is a threat."

For its part, the Kremlin has kept repeating the line that it considers NATO to be at war with Russia.

While NATO says that this is not the case, Admiral Bauer told DW that the alliance is in "a gray zone between peace and war" and on high alert: "This is a very important message to Mr. Putin: NATO will respond, whatever happens."

Bauer says that allied defenses proved that they work when they shot down the drones over Poland: "I think we passed the test, but we have to become better in addressing these new threats," he told DW.

The CER's Ian Bond is skeptical about NATO's current drone defense capabilities. "The impression is that NATO was not prepared for shooting down drones, and it needs to step up its game considerably," he told DW.

Bond said that NATO needs to show more resolve and take down Russian drones whenever it can be safely done -- even if they are flying over western Ukraine.

NATO member states have so far refrained from doing so in several cases.

In July, Lithuania reported that two Russian drones had crossed into its airspace but it did not shoot them down. In a statement cited in Lithuanian media, the military reported it would only take such measures in extreme circumstances. Following the incident, Lithuania asked NATO for increased air defenses.

Most recently, Romania did not take active measures against a Russian drone in its airspace, which then changed course and headed toward Ukraine. According to Romania's Ministry of Defense, Romanian Air Force pilots who spotted the drone "assessed the collateral risks and decided not to open fire."

Bond warns that Moscow might read such inaction as an encouraging sign, and that drones like these could well go on to strike targets in Ukraine.

While intercepting drones is key to defending NATO's airspace, experts also say that governments should be thinking about measures such as air raid warning apps and increased shelter capacity.

"It would be a terrifying new step, but I don't think it's an excessive step," defense analyst Ian Bond told DW.

He is convinced that Russia will continue to test Ukraine's western allies unless they significantly ramp up their own defenses and their support for Ukraine.

Kremidas-Courtney shares this assessment, saying "We should assume Russia is going to try this every couple of weeks, until we make them pay a price that makes them decide not to."

NATO hopes that Operation Eastern Sentry will do just that.

Is NATO ready for drone warfare?