Inflatable air mattresses greeted air travelers arriving yesterday at Moscow’s Sheremetyevo Airport, Russia’s busiest. One thousand miles to the west, long waits in hard plastic chairs greeted air travelers arriving at Copenhagen’s Katrup airport, Scandinavia’s busiest.

In both cases, the culprits were the same: drones. Ukrainian military drones attacked Moscow. Mystery drones, presumably flying from Russian cargo ships in the Baltic Sea, interrupted almost 200 flights in and out of Oslo and Copenhagen, two cities 300 miles apart. Long confined to remote eastern Ukraine, the war between Russia and Ukraine is starting to be felt in the rest of Europe.

The two or three drones that repeatedly sailed over Copenhagen’s airport had wingspans of at least eight feet. This would indicate a state actor, as large drones are launched with catapults or rails. Almost to show off, the operators turned the drones’ lights on and off. Prime Minister Mette Frederiksen of Denmark told reporters yesterday:“The police assess that this is a capable actor.”

The airport is adjacent to a busy Baltic shipping lane. Last night, Denmark’s TV2 channel reported that two ships sanctioned for carrying Russian cargo — the Astrol 1 and the Pushpa — were near the airport at the time of the interference. On the other side of the shipping channel, Sweden is investigating suspicious drone sightings over two Swedish cities, Malmö and Lund.

“What we saw last night is the most serious attack on Danish critical infrastructure to date,” Mr. Frederiksen said. “It is clear that this fits in with the developments we have observed recently with other drone attacks, violations of airspace, and hacker attacks on European airports.”

On Friday, a mysterious cyber attack hit North Carolina-based Collins Aerospace. Sabotage of this American aviation company disrupted check-in and boarding at three of Europe’s busiest airports: Heathrow, Brussels, and Berlin.

Yesterday’s drone disruptions at the two Scandinavian airports follow Russian air space violations this month by drones or war jets of Estonia, Latvia, Lithuania, Poland, and Romania. Norway says that Russia has violated its airspace three times this year, breaking a 10-year pause.

“We can’t determine whether this was done deliberately or whether it was due to navigation errors,” Prime Minister Jonas Gahr Stoere of Norway said yesterday. “Regardless of the reason, this is not acceptable and we have made that clear to Russian authorities.”

Yesterday, for the second time this month, ambassadors of the North Atlantic Treaty Organization met to discuss the problem. In the previous 76 years of the North Atlantic Treaty, members met only seven times under the consultative clause, Article IV.

“Russia bears full responsibility for these actions, which are escalatory, risk miscalculation and endanger lives. They must stop,” the 32-nation NATO council said. “Russia should be in no doubt: NATO and Allies will employ, in accordance with international law, all necessary military and non-military tools to defend ourselves and deter all threats from all directions.” Secretary General Mark Rutte of NATO told reporters: “We are a defensive alliance, yes, but we are not naive.” 

European newspapers have started publishing maps showing the 1,500-mile range of Russia’s mass-produced Geran-2 drones. If launched from Russia’s Kaliningrad exclave, they could hit Portugal. Today, a Spanish military jet with the defense minister, Margarita Robles, onboard suffered a GPS “disturbance”while flying near Kaliningrad  on its way to Lithuania, the ministry said,

“European leaders must take the Russian drone threat seriously,” a strategic policy analyst, Maksym Beznosiuk, wrote yesterday in an Atlantic Council essay. “There is no time to waste. European countries cannot wait until Russia goes even further before addressing the urgent security concerns raised by the Kremlin’s drone diplomacy.”

Criticism of Russia came from an unexpected quarter — Germany’s hard-right leader, Alice Weidel. She said in Berlin: “I believe that Russia should also strive for de-escalation, not violate NATO airspace and not test NATO air defense systems.” 

At New York, at the United Nations, it was clear yesterday that Western leaders are drawing a red line to deter Russia from pushing its war west. A reporter asked President Trump if he thought members of the North Atlantic Treaty should shoot down Russian aircraft in their airspace. He responded tersely: “Yes I do.” 

America’s new envoy to the United Nations, Michael Waltz, used his debut remarks Monday before the Security Council to state: “The United States stands by our NATO allies in the face of these airspace violations. I want to take this first opportunity to repeat and to emphasize that the United States and our allies will defend every inch of NATO territory.” 

Yesterday, Secretary Pete Hegseth called the Estonian defense minister, Hanno Pevkur, and said that the Trump administration “stands with all NATO allies and that any incursion into NATO airspace is unacceptable.” Estonia’s foreign minister, Margus Tsahkna, had complained that the three Russian warplanes that lingered over Estonia for 12 minutes last week were “carrying missiles and were combat-ready.”

In Lithuania, the largest Baltic nation, the parliament voted overwhelmingly yesterday to give its armed forces the power to shoot down any unmanned drone violating its airspace. Latvia’s president, Edgars Rinkevics, told Bloomberg yesterday: “If Russian aircraft keep flying, keep violating our airspace, NATO airspace, the only way to stop them is with a show of force.”

Across the Baltic, the Swedish defense minister, Pål Jonson, said yesterday that “no country has the right to violate Swedish airspace. Sweden has the right to defend its skies, with force if necessary, and will do so.”

From the Russian side, Ukrainian drones have disrupted commercial air travel all summer long. Yesterday Moscow’s mayor, Sergei Sobyanin, reported on Telegram that air defenses shot down 33 Ukrainian drones flying toward the capital. As more than 10 explosions were heard yesterday around Moscow, travelers arrived at Sheremetyevo to find that airport officials had preemptively invested in inflatable blue velour air mattresses. This time, internet videos of passengers stretched out on plush mattresses replaced earlier images of stranded travelers trying to sleep on hard floors.

“We won’t be partaking in this theater of the absurd,” Russia’s deputy ambassador to the UN, Dmytry Polyanskiy, protested to reporters at New York yesterday.  “When you decide that you want to engage in a serious discussion about European security, about the fate of our common continent, about how to make this continent prosperous and secure for everybody, we’ll be ready.”

Russian testiness may be in response to a Security Council statement Monday by Poland’s foreign minister, Radek Sikorski. “If another Russian missile or aircraft enters our airspace and gets shot down, don’t come here to whine,” he said, staring across the hall at the Russian delegation. “You have been warned.”