Fueling the turnout Sunday of, by police estimates, 150 demonstrators is "a lot of apprehension," said Odarka Begej of Maple Glen, who was born in Canada to Ukrainian parents.
Speakers included members of the Georgian, Lithuanian, Latvian, Russian, Polish, Tajikistani, Belarusian, and Ukrainian Jewish communities.
"We contacted everybody," said organizer Iryna Mazur, 37. "It's not only a matter between Ukraine and Russia."
"In three months it just turned upside down," said Maksym Dyeyev, 26, of Malvern, a graphic designer who came to the United States from Ukraine with his parents five months ago. "Nobody was expecting this."
Russian troops arrived Friday in Crimea, an autonomous region of eastern Ukraine with strong allegiance to neighboring Russia, and surrounded the airport in Sevastopol, the site of a Russian naval base. Armed, uniformed men have also occupied the airport and surrounded government buildings in Simferopol, Crimea's capital.
Russia said the move was to protect the ethnic Russians in the region, believed to make up more than 50 percent of the population. But Prime Minister Yatsenyuk denounced the move as an act of aggression.
President Obama had a 90-minute phone call with Russian President Vladimir Putin on Saturday, the White House announced, calling his country's military occupation a "clear violation of Ukrainian sovereignty and territorial integrity." Secretary of State John Kerry, who has suggested sanctions by the Group of 8 against Russia, will meet with the interim Ukrainian leadership in Kiev Tuesday.
At the Philadelphia rally Sunday, many participants tied blue-and-yellow flags around their shoulders, while some women wore flower wreaths in their hair.
Protester Olena Mishchuk, 31, of Northeast Philadelphia, said the turnout was larger than last Sunday's.
Among the new faces was Nikita Khorkov, 23, who arrived from Kiev last week. He had been in the Maidan, the opposition forces' camp in the city's Independence Square.
"I was not protected because I didn't have a gun or a helmet. It was very scary," said Khorkov, an officer in the Ukrainian army. "Police were shooting people. "
Yanukovych, the president, was ousted late last month, after protesters began taking over government buildings. The uprising began in November in response to Yanukovych's rejection of a trade agreement with the European Union, in favor of closer economic ties with Russia. The protests turned deadly in January.
Khorkov spent much of the Philadelphia rally holding a banner that read: "No War in Ukraine!!!!"
"We're trying to get attention from the American government," Khorkov said. If war erupts, he said, he will have to return and fight. "Any help would help."
Southeastern Pennsylvania's Ukrainian community is very active, protesters said, and word spread about the day's rally through e-mail chains, Facebook, and phone calls. Of the nearly one million people of Ukranian descent in the United States, 122,000 live in Pennsylvania and 74,000 in New Jersey.