(NECN: Brian Burnell, Boston) - Russian boots on the ground in Ukraine, including troops surrounding a military base there, have the world on edge.
Ukraine's acting prime minister, Arseniy Yatsenyuk, is calling for international help.
"This is actually the declaration of war to my country," said Yatsenyuk.
NATO held an emergency meeting in Brussels, and Great Britain's foreign minister flew to Kiev to support the new government. Secretary of State John Kerry will follow on Tuesday.
On Sunday's morning news shows, Kerry called Russia's reasoning to protect Russian-speaking citizens in Crimea a lie.
"You just don't invade another country on phony pretexts in order to assert your interests," said Kerry.
President Obama spent 90 minutes on the phone with Russian President Vladimir Putin Saturday, with Obama saying the invasion is unacceptable. He is threatening economic and political isolation.
"Absolutely all options should be on the table, including military aid to Ukraine," said Ukrainian student Oleh Kotsyuba at a protest at Boston's Faneuil Hall. "I don't think just economic sanctions will be enough. Putin is effectively a bully, and as a bully, he will understand only the language of force."
At demonstrations across the country, Ukrainian supporters called for tougher talk from President Obama.
Ilya Timtchenko organized Sunday's rally in Boston. He says Putin's goal is not war with Ukraine.
"What he's trying to do is he's trying to start a civil war within Ukraine so that after Ukraine destroys itself within and once it becomes weak enough then he can victoriously come in and save the Russians within Ukraine."
Demonstrators in Boston told NECN they do not want western boots on the ground in Ukraine. They want tougher talk from President Obama and a promise that if the Ukrainian military calls for aid, they will get it, even if that means delivering weapons systems.