Residents of Kyiv woke up to air raid sirens as Ukraine observed its Independence Day on Wednesday, which also marked exactly six months since the start of Russia's military invasion.

Authorities in the capital banned large-scale gatherings until Thursday, fearing the national holiday might bring particularly heavy Russian missile attacks. Ukrainian President Volodymyr Zelenskyy urged the public to be vigilant.

“Russian provocations and brutal strikes are a possibility,” Zelenskyy said in a statement. “Please strictly follow the safety rules. Please observe the curfew. Pay attention to the air sirens. Pay attention to official announcements. And remember: We must all achieve victory together.”

A small number of residents gathered at Kyiv's central square, where destroyed Russian tanks and mobile artillery were put on display over the weekend, and the national anthem is played every day at 7 a.m. local time.

“I can’t sleep at night because of what I see and hear about what is being done in Ukraine," a retiree who identified herself only by her first name, Tetyana, said, her voice shaking with emotion.

“This is not a war. It is the destruction of the Ukrainian people," she said.

Wednesday’s holiday commemorates Ukraine’s 1991 declaration of independence from the Soviet Union.

“Six months ago, Russia declared war on us. On February 24, all of Ukraine heard explosions and gunshots. ... On February 24, we were told: You have no chance. On August 24, we say: Happy Independence Day, Ukraine!” Zelenskyy said in an Independence Day message.

A car bombing outside Moscow that killed the 29-year-old daughter of right-wing Russian political theorist Alexander Dugin on Saturday heightened fears that Russia might intensify attacks on Ukraine this week.

Read:On eve of Ukraine's national day, fears Russia will pounce

Russian officials have blamed Ukraine for the death of Darya Dugina, a nationalist Russian TV commentator. The car bomb exploded after she had attended a patriotic festival with her father, whom was widely believed to have been the intended target.

The Ukrainian government has denied any involvement.

Russian President Vladimir Putin ordered tens of thousands of troops into Ukraine on Feb. 24. Moscow's military encountered unexpectedly stiff Ukrainian resistance, and the six months of fighting has upended life in Ukraine and sent shock waves through the world economy.

As the war reached its 182nd day, there was no sign of a quick end to the conflict, which NATO Secretary-General Jens Stoltenberg on Tuesday described as “ a grinding war of attrition.” Russia now holds large swaths of the country’s east and south, but its gains accumulated slowly. Neither country has revealed how many troops it has lost during the six-month conflict.

The United States is expected on Wednesday to announce roughly $3 billion in additional aid to train and equip Ukrainian forces to fight for years to come, U.S. officials said.

The officials told The Associated Press the package would fund contracts for as many as three types of drones and other weapons, ammunition and equipment that may not see the battlefront for a year or two.

The new funding is largely aimed at helping Ukraine secure its medium- to long-term defense posture, according to officials familiar with the matter. Earlier shipments focused on Ukraine’s more immediate needs for weapons and ammunition and involved materiel the Pentagon already had in stock that could be shipped quickly.

Several officials spoke on condition of anonymity to discuss the aid package before a public announcement.

On the forefront of the Russian offensive in eastern Ukraine, the conflict ground on. Russian forces struck several towns and villages in Donetsk province over 24 hours, killing one person and injuring another two, according to the regional administration.

In the Dnipropetrovsk region on the southern front, Russian forces again shelled the cities of Nikopol and Marhanets, damaging several buildings and injuring two people, according to Gov. Valentyn Reznichenko. Russian troops also shelled the city of Zaporizhzhia, damaging several buildings and infrastructure but inflicting no casualties.