Russian strikes hit near airports in western Ukraine on Friday as the military offensive widened, and invading troops kept up pressure on the capital Kyiv and the besieged port city of Mariupol.

The airstrikes on the Lutsk military airfield left two Ukrainian servicemen dead and six people wounded, according to the head of the surrounding Volyn region, Yuriy Pohulyayko.

The strikes also targeted an airport near Ivano-Frankiivsk, where residents were ordered to shelters after an air raid alert, Mayor Ruslan Martsinkiv said.

New satellite photos, meanwhile, appeared to show a massive convoy outside the Ukrainian capital had fanned out into towns and forests near Kyiv with artillery pieces raised for firing in another potentially ominous movement.

The photos emerged amid more international efforts to isolate and sanction Russia, particularly after a deadly airstrike on a maternity hospital in the port city of Mariupol that Western and Ukrainian officials decried as a war crime. The United States and other nations were poised Friday to announce the revocation of Russia’s "most favored nation" trade status, which would allow tariffs to be imposed on Russian imports.

Unbowed by the sanctions, Russia kept up its bombardment of Mariupol while Kyiv braced for an onslaught, its mayor boasting that the capital had become practically a fortress protected by armed civilians.

Satellite imagery from Maxar Technologies showed that the 40-mile (64-kilometer) convoy of vehicles, tanks and artillery has broken up and been redeployed, the company said. Armored units were seen in towns near the Antonov Airport north of the city. Some of the vehicles have moved into forests, Maxar reported, with towed howitzers nearby in position to open fire.

The convoy had massed outside the city early last week, but its advance appeared to stall as reports of food and fuel shortages circulated. U.S. officials said Ukrainian troops also targeted the convoy with anti-tank missiles.

Still, the immediacy of the threat to Kyiv was unclear. A U.S. defense official speaking on condition of anonymity said Russian forces moving toward Kyiv had advanced about 5 kilometers in the past 24 hours, with some elements as close as 15 kilometers from the city.

The official gave no indication that the convoy had dispersed or otherwise repositioned in a significant way, saying some vehicles were seen moving off the road into the tree line in recent days.

In Mariupol, a southern seaport of 430,000, the situation was increasingly dire as civilians trapped inside the city scrounged for food and fuel. More than 1,300 people have died in the 10-day siege of the frigid city, said Deputy Prime Minister Iryna Vereshchuk.

Residents have no heat or phone service, and many have no electricity. Nighttime temperatures are regularly below freezing, and daytime ones normally hover just above it. Bodies are being buried in mass graves. The streets are littered with burned-out cars, broken glass and splintered trees.

"They have a clear order to hold Mariupol hostage, to mock it, to constantly bomb and shell it," Ukrainian President Volodymyr Zelenskyy said in his nightly video address to the nation. He said the Russians began a tank attack right where there was supposed to be a humanitarian corridor.

On Thursday, firefighters tried to free a boy trapped in the rubble. One grasped the boy's hand. His eyes blinked, but he was otherwise still. It was not clear if he survived. Nearby, at a mangled truck, a woman wrapped in a blue blanket shuddered at the sound of an explosion.

Grocery stores and pharmacies were emptied days ago by people breaking in to get supplies, according to a local official with the Red Cross, Sacha Volkov. A black market is operating for vegetables, meat is unavailable, and people are stealing gasoline from cars, Volkov said.

Places protected from bombings are hard to find, with basements reserved for women and children, he said. Residents, Volkov said, are turning on one another: "People started to attack each other for food."

An exhausted-looking Aleksander Ivanov pulled a cart loaded with bags down an empty street flanked by damaged buildings.

"I don’t have a home anymore. That’s why I’m moving," he said. "It doesn’t exist anymore. It was hit, by a mortar."

Repeated attempts to send in food and medicine and evacuate civilians have been thwarted by Russian shelling, Ukrainian authorities said.

"They want to destroy the people of Mariupol. They want to make them starve," Vereshchuk said. "It’s a war crime."

Russian-backed separatists have captured the Ukrainian city of Volnovakha north of the besieged Azov Sea port of Mariupol, the RIA news agency quoted Russia's Defense Ministry as saying on Friday. Volnovakha is strategically important as the northern gateway to Mariupol

Russian Defense Ministry spokesperson Igor Konashenkov said Friday that Russian forces had destroyed 3,213 Ukrainian military installations since the launch of what Russia calls a "special military operation" in Ukraine.

The number of refugees fleeing the country has topped 2.3 million, and some 100,000 people have been evacuated during the past two days from seven cities under the Russian blockade in the north and center of the country, including the Kyiv suburbs, Zelenskyy said.

Zelenskyy told Russian leaders that the invasion will backfire on them as their economy is strangled. Western sanctions have already dealt a severe blow, causing the ruble to plunge, foreign businesses to flee and prices to rise sharply.

"You will definitely be prosecuted for complicity in war crimes," Zelenskyy said in a video address, warning that, "You will be hated by Russian citizens."

Russian President Vladimir Putin dismissed such talk, saying the country has endured sanctions before.

″We will overcome them," he said at a televised meeting of government officials. He did, however, acknowledge the sanctions create "certain challenges."

In addition to those who have fled the country, millions have been driven from their homes inside Ukraine. Kyiv Mayor Vitali Klitschko said about 2 million people, half the population of the metropolitan area, have left the capital.

"Every street, every house... is being fortified," he said. "Even people who in their lives never intended to change their clothes, now they are in uniform with machine guns in their hands."

On Thursday, a 14-year-old girl named Katya was recovering at the Brovary Central District Hospital on the outskirts of Kyiv after her family was ambushed as they tried to flee the area. She was shot in the hand when their car was raked with gunfire from a roadside forest, said her mother, who identified herself only as Nina.

The girl’s father, who drove frantically from the ambush on blown-out tires, underwent surgery. His wife said he had been shot in the head and had two fingers blown off.

Western officials said Russian forces have made little progress on the ground in recent days and are seeing heavier losses and stiffer Ukrainian resistance than Moscow apparently anticipated. But Putin’s forces have used air power and artillery to pummel Ukraine's cities.

Early in the day, the Mariupol city council posted a video showing a convoy it said was bringing in food and medicine. But as night fell, it was unclear if those buses had reached the city.

A child was among three people killed in the hospital airstrike Wednesday. Seventeen people were also wounded, including women waiting to give birth, doctors, and children buried in the rubble. Images of the attack, with pregnant women covered in dust and blood, dominated news reports in many countries.

French President Emmanuel Macron called the attack "a shameful and immoral act of war." Britain’s Armed Forces minister, James Heappey, said that whether the hospital was hit by indiscriminate fire or deliberately targeted, "it is a war crime."

U.S. Vice President Kamala Harris, on a visit to Ukraine's neighbor Poland, backed calls for an international war-crimes investigation into the invasion, saying, "The eyes of the world are on this war and what Russia has done in terms of this aggression and these atrocities."