‘We are frustrated, and we are terrified’: Ukrainian expats express solidarity with their homeland.

About 200 people, mostly expatriates from Ukraine, gathered in London on Saturday to express solidarity with friends and family in the country who are living under the threat of a Russian invasion.

The rally convened at the foot of a statue of Volodymyr the Great, who ruled a region including modern-day Ukraine during the 10th and 11th centuries and is a symbol of Ukrainian nationalism. Under a cloudy sky, the demonstrators waved Ukrainian flags, sang nationalist songs and held aloft placards demonizing President Vladimir V. Putin of Russia.

Many of the attendees said that they were clinging to the hope that a full-scale Russian invasion could be averted but that all signs suggested their homeland was on the brink of a terrible ordeal.

“The country I know and love might be destroyed,” said one of the rally’s organizers, Natalia Ravyluk, who is originally from Ukraine. “We are frustrated, and we are terrified.”

She said she feared that the recent American-led efforts to deter a Russian attack through diplomacy would not be enough.

“We have gathered like this every year since 2014, hoping we can help people remember the plight of Ukraine,” Ms. Ravyluk said, referring to the year that Russia annexed Crimea. “Now it feels like it is too late.”

The mounting tensions were echoed in the worried faces in the crowd, a mix of recent immigrants and Londoners of Ukrainian descent.

Some carried placards with Mr. Putin described as “Terrorist #1” or with messages such as, “Russia, hands off Ukraine.” Others wore Ukrainian flags draped over their shoulders. One group placed a pockmarked helmet and gas mask at the foot of Volodymyr the Great’s statue, forming a makeshift shrine. A few shed tears.

Vadym Prystaiko, Ukraine’s ambassador to Britain, was also present. “Many people here believe that Putin may finally be close to finishing what he started several years ago,” he said.

While much of the demonstrators’ fury was directed at Mr. Putin, some said they felt torn — relieved to be living in peace in London while also wanting to join their compatriots during this moment of peril.

“We are constantly plagued by this inner conflict — wanting to exchange our own safety for the safety of our families back home,” Diana Vartanova, one of the demonstrators, said.

Ms. Vartanova, 26, who moved to London 10 years ago, is from the eastern region of Zaporizhzhia. In the past few weeks, she said, she has wavered “somewhere between feeling optimistic and completely panicked.” After the British government released maps this week identifying possible routes of a Russian invasion, the reality of her family’s proximity to the front lines set in.

“After years of uncertainty, it feels like war is truly knocking on our door,” she said.

Toward the end of the ceremony on Saturday, a group of men dressed in dark clothing posed for photographs in front of the statue of Volodymyr. Some said they had served in the military in Ukraine and had been training twice a month at a camp outside London.

“You could say I’ve been waiting for this moment,” said one of the men, Roman Azarov, a former military officer who left Ukraine 20 years ago. Mr. Azarov shared photographs of himself engaged in military training, which he said he was ready to put to use. He said that he was in touch with many of his old army friends back home and that they were preparing to defend their country if a Russian invasion came.

“As soon as I get the word,” he said. “I will go.”