House Republicans are calling on President Obama to declare whether Russia has invaded Ukraine, after reports that at least a thousand Russian troops have illegally entered Ukraine.
"The President needs to definitively state whether or not Russia has invaded Ukraine and immediately condemn this overt escalation of an already serious conflict," said House Armed Services Committee Chairman Buck McKeon (R-Calif.) and Rep. Michael Turner (R-Ohio) in a joint statement.
"If reports prove accurate that Putin has in fact sent over 1,000 troops into Ukraine to support and fight alongside Russian-backed separatists, this is an act of war against the sovereign state of Ukraine," they wrote.
State Department spokeswoman Jen Psaki stopped short of calling the Russian action an invasion or act of war on Thursday, instead describing it as "escalating aggression."
"It’s clear that Russia has not only stepped up its presence in eastern Ukraine and intervened directly with combat forces, armored vehicles, artillery and surface-to-air systems, and is actively fighting Ukrainian forces as well as playing a direct supporting role to the separatist proxies and mercenaries," Psaki said.
Psaki said the U.S. had no reason to doubt a NATO assessment that at least a thousand Russian troops had crossed the border, although she said the State Department could not independently confirm that figure.
She added that the troop movement was of "concern" to the U.S. and said the administration and its allies were weighing a "range of tools" — including stepped up economic sanctions — in response.
Psaki added that the possibility of providing Ukraine with military assistance remained on the table, but said the preference and priority of the U.S. was nonlethal aid and a diplomatic solution.
Ukraine National Security Council spokesman Col. Andriy Lysenko said Thursday that two convoys of Russian tanks and military vehicles had rolled into southeastern Ukraine, as Ukrainian border guards fled.
Russia's defense ministry has denied the reports.