An American factory in western Ukraine. Two European diplomatic compounds and a key Ukrainian government building in Kyiv. And now Poland.

Over a roughly three-week period, Russian drones and missiles have struck sites of increasing sensitivity for Ukraine and its Western allies, culminating in the volley of Russian drones that buzzed early Wednesday over Poland, a NATO country.

For decades, American and European military planners feared something else: a bolt-from-the-blue assault, like an all-out nuclear strike, from the Soviet Union or Russia. But in its war on Ukraine, Russia has walked over a Western red line gradually, gauging responses as it goes, blunting any pushback by escalating slowly and maintaining some level of deniability, according to Ukrainian officials and analysts.

The drones that flew into Poland prompted NATO to send warplanes to shoot them down, in the first direct engagement of the alliance’s troops with Russian weaponry since Russia invaded Ukraine in 2022. But none of the previous Russian attacks in recent weeks led to more than strongly worded statements from European or U.S. officials, and it was unclear if Russia would pay any real price for its incursion into Poland.

“Russian drones flying into Poland during the massive attack on Ukraine show that Putin’s sense of impunity keeps growing,” Ukraine’s foreign minister, Andrii Sybiha, said in a statement about the incident, speaking of President Vladimir V. Putin. “He was not properly punished for his previous crimes.”

Mr. Putin has become “emboldened,” Katarina Mathernova, the European Union’s ambassador to Ukraine, said in an interview at the delegation’s office in Kyiv, where windows were cracked by shrapnel from a Russian attack two weeks ago.

The Russian leader has so far faced no consequences for continuing the war unabated, Ms. Mathernova said, only increasing the Kremlin’s military assaults after his summit in Alaska last month with President Trump.

Russia is fighting at or close to the limits of its conventional military capacity in Ukraine, analysts say, giving it a limited ability to escalate in real military terms. But symbolic moves like aerial attacks on Western assets in Ukraine or drone flights across a NATO border test military defenses and send a message of strength, analysts say.

As it ramps up its provocations bit by bit, Russia has worked to leave room for doubt in the strikes.

The American-owned factory that was severely damaged by Russian missiles last month in western Ukraine made coffee machines, but other factories like it are dual-use facilities that also produce military goods.

The two Russian missiles that blew out windows and sprayed shrapnel on the facades of the offices of the European Union and the British Council in Kyiv hit not the diplomatic sites but a building nearby.

When a Russian missile set fire to Ukraine’s Cabinet of Ministers building on Sunday morning, even the mayor of Kyiv said that it might have veered off course, before other Ukrainian officials called the attack intentional. That attack appeared to signal that any Western troops eventually stationed in Ukraine to protect its government would be at risk.

And after the drones entered Polish airspace on Wednesday, a Russian ally, Belarus, issued a statement suggesting they had crossed the border by accident.

The United States and European allies, too, have inched over red lines in the war. The United States, Britain and France have provided long-range rockets and missiles to Ukraine’s army. The United States did so at first with a firm prohibition against their use on Russian territory, blunting Moscow’s initial objections, only later to allow limited attacks inside Russia.

Russia has long employed strategies of misdirection and denial, age-old staples of war. The Kremlin began its initial invasion of Ukraine in 2014 with a simple ruse of deploying soldiers onto the Crimean Peninsula who were wearing masks and uniforms without insignia.

However rudimentary, the mystery around the soldiers, who became known in Ukraine as the “little green men,” blunted Western responses for days.

Over the past half century, nearly every Russian military operation in a foreign country has begun with deploying soldiers in civilian clothes or unmarked uniforms, from the crackdown on the Prague Spring uprising in 1968 in Czechoslovakia to the conflicts in Afghanistan, Chechnya and Ukraine.

In 2015, Russia described transport planes flying to the Middle East as a “humanitarian airlift” before acknowledging its military intervention in Syria.

And after the drones entered Polish airspace, the chargé d’affaires at the Russian Embassy in Poland, Andrey Ordash, told the Russian news agency Tass, “We know one thing, these drones flew from Ukraine.”

“Lies and denials are default Soviet responses,” Poland’s deputy prime minister and defense minister, Radoslaw Sikorski, said in a video statement posted on X.

An adviser to Ukraine’s presidential office, who spoke on the condition of anonymity to discuss internal Ukrainian thinking, said Kyiv believed that even an unacknowledged attack by Moscow could bring negotiating advantages in an “escalate to de-escalate” strategy.

Russia might offer Poland and Warsaw’s alarmed allies in NATO an assurance against future incursions, framed as a concession in talks to end the war in Ukraine, the Ukrainian adviser said.