Several nights a week, Daria Slavytska packs a yoga mat, blankets and food into a stroller and descends with her two-year-old Emil into the Kyiv subway. While air raid sirens wail above, the 27-year-old tries to snatch a few hours' sleep safely below ground.

For the past two months, Russia has unleashed nighttime drone and missile assaults on Kyiv in a summer offensive that is straining the city's air defences, and has its 3.7 million residents exhausted and on edge.

Other towns and villages have seen far worse since Russia launched its full-scale invasion in early 2022 - especially those close to the frontline far to the east and south.

Many have been damaged or occupied as Russia advances, and thousands of people have fled to the capital, considered the best-defended city in the country.

But recent heavy attacks are beginning to change the mood. At night, residents rush to metro stations deep underground in scenes reminiscent of the German "Blitz" bombings of London during World War Two.

Slavytska has started nervously checking Telegram channels at home even before the city's alarms sound, after she found herself in early July running into the street to reach the metro with explosions already booming in the sky.

The number of people like Slavytska taking refuge in the cavernous Soviet-era ticket halls and drafty platforms of Kyiv's 46 underground stations soared after large-scale bombardments slammed the city five times in June.

Previously, the loud air raid alert on her phone sent Emil into bouts of shaking and he would cry "Corridor, corridor, mum. I'm scared. Corridor, mum," Slavytska said. Now, accustomed to the attacks, he says more calmly "Mum, we should go".

"We used to come here less often, about once a month," Slavytska said, sheltering in Akademmistechko station in western Kyiv. "That was six months ago. Now we come two or three times a week." She spent the night curled up on her pink mat with Emil by a column lining the subway tracks.

The subway system recorded 165,000 visits during June nights, more than double the 65,000 visits in May and nearly five times the number in June last year, its press service told Reuters.

More people were heading to the shelter because of "the scale and lethality" of attacks, the head of Kyiv's military administration, Tymur Tkachenko, told Reuters. He said strikes killed 78 Kyiv residents and injured more than 400 in the first half of the year.

U.S. President Donald Trump cited Russia's strikes on Ukrainian cities when announcing his decision on Monday to offer Kyiv more weapons, including Patriot missiles to boost its air defences.

"It's incredible that (people) stay, knowing that a missile could be hitting your apartment," Trump said.