In the Ukrainian port city of Odessa, residents recently hid not from the thunder of rocket attacks, but from the hum of Iranian drones in the sky.

The machines have played an important role since Russia’s invasion seven months ago – as part of reconnaissance operations, rocket fire or bombing.

Maryna Kondratieva, startled by a loud roar from the sky on Saturday morning, ran to hide in the basement with her two young children, fearing the worst.

“I understand now that everything can change in five minutes,” Kondratieva, who lives in an affluent part of the city and whose terrace overlooks the Black Sea, told AFP.

Odessa – the “capital” of the southwest and Ukraine’s main port – appeared largely safe from Moscow, whose troops failed to capture it early in the war.

The sandbags and other checkpoints that had ravaged the Old City were largely removed, and bombings became less frequent.

But an increasing number of drones taking to the skies has city dwellers fearing a return to darker days.

In a video shot by Kondratyeva’s husband and shown to AFP, a drone continues to fly around her home, accompanied by the sound of heavy gunfire.

Kondratieva recently returned to Ukraine from Cyprus after taking refuge with her in-laws with her five and six-year-olds.

The successful counteroffensive by Kievan forces in the northeast, more sluggish in the south, had restored hope.

Hearing the drone’s “buzz around the house” made her feel like war was once again very close to home.

Since Kyiv claims it shot down its first Iranian drone, about “two dozen” have been sighted in southern Ukraine since September 13, military spokeswoman Nataliya Houmeniouk told AFP.

Half of them have been neutralized, she said.

Russia’s drone industry has been hit by international sanctions and some have been shot down since the war began – prompting Moscow to import drones from Iran.

Iran’s observation and attack machine Mohajer-6 and its Shahed-136 (“Martyr-136”) – small kamikaze drones with a very long range of 2,500 kilometers – were “likely” involved in attacks in the Middle East last summer, including against an oil tanker in the Gulf of Oman, according to a statement from the British Ministry of Defence.

The shahed are “very difficult to spot because they fly very low. But they make a lot of noise, like a chainsaw or a scooter,” meaning they can be heard from afar, Houmeniouk said.

Although their effectiveness is “very low,” they primarily “put psychological pressure on the population,” she added.

“The Iranian defense industry tends to prioritize affordability over quality control, so their systems typically suffer from a fairly high failure rate as part of that trade-off,” Jeremy Binnie, an analyst at Britain’s Janes Defense Intelligence Group, told AFP.

The Shahed targets are also tracked by GPS, and “these have a very long range but a relatively small warhead,” he said.

Their effectiveness will depend on Russian military intelligence’s ability to pinpoint the coordinates of suitable targets behind front lines, Binnie said — something difficult to accomplish without proper reconnaissance aircraft.

At least for now, he said, the Iranian drones would not have a major impact on the war.

Ukraine has partially relied on the ingenuity of civilians who have turned quasi-toy drones into weapons of war.

Turkey’s popular Bayraktar TB2 drones have also carried out attacks on the Russians – gaining such domestic fame in the process that a song was made about them on social media.

And Kyiv has also deployed American kamikaze machines, the switchblades, whose onboard cameras show them crashing into a surprised enemy.

But while Russian drones may not be a vital part of the war effort, their use is having a significant psychological impact on war-weary Ukrainian civilians.

Former businesswoman Iryna Koroshenkaya moved to Odessa to find some semblance of rest.

Originally from Mykolayiv, two hours away, where Russian strikes continue daily, the 57-year-old says she was “slung against a garage” by a bomb blast in April.

On Sunday morning, she heard an anti-aircraft alert and two explosions before watching a drone hum over a 23-story building from her balcony.

Another new explosion followed, and a “large plume of smoke,” she recalled.

For Koroshenkaja, the drones are associated with a recurring sense of “fear.”

“What will happen next?” she asked. “Will Odessa stay safe?”