In a significant escalation of the conflict, Ukraine struck the Moscow region on Tuesday in its most significant drone attack so far on the Russian capital, killing at least one woman and wrecking dozens of homes. It also forced the closure of three of Moscow’s airports and diverted around 50 flights.

The strikes, which began overnight and lasted into Wednesday, were conducted by Ukrainian military aircraft as well as uncrewed aerial vehicles or drones. The military said they involved some 140 units. It said drones were used to target two high-rise apartment buildings in the Ramenskoye district, setting them on fire and forcing the evacuation of 43 people.

A 46-year-old woman died, and three others were injured in the attack. Local authorities said that drones also hit two residential buildings outside Moscow in the city of Zhukovsky and sparked blazes. Videos circulating on social media showed flames shooting out of windows at the two multistory buildings. The airports in the capital and Zhukovsky were closed for several hours, Russia’s aviation authority Rosaviyatsia said.

Shortly afterward, three of the capital’s four airports operated again, but flights to and from them had been diverted. A major road into the city was closed. The Kremlin denied involvement in the strikes.

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Ukraine and Russia both have fast-tracked the development of domestic drones, which are cheap to buy but can be modified to carry deadly payloads. They have also developed ways to destroy them — from shotguns to sophisticated electronic jamming systems.

To insulate its population from the grinding rigor of the war, Russia has been building up its nuclear arsenal and has promised to strike back deep into Ukraine. Kyiv’s Western backers, however, do not want a full-scale war between the West and Russia.

Both sides are seeking to gain a technological advantage. Ukraine’s new generation of drones is equipped with gyroscopes and inertial measurement units, which give them excellent stability. Ukraine’s drones are also capable of tracking and attacking moving targets, including aircraft and tanks, which gives them a potentially deadly edge over their Russian counterparts.

On Aug. 6, Kyiv launched a bold strike on Russia’s western Kursk region and has been launching increasingly large drone attacks deeper into Russian territory. Russia says such attacks are akin to “terrorism” and has threatened a response. It has already pounded Ukraine with thousands of missiles and drones in the past two and a half years, devastating cities like Moscow and other prominent Russian towns and wreaking havoc on civilian infrastructure. Both sides have been accused of widespread violations of international law and human rights.