Obama speaks at Africa Leaders Summit

President Barack Obama answers questions during his news conference following the U.S.-Africa Leaders Summit. (Alex Wong / Getty Images / August 6, 2014)

President Obama said on Wednesday Ukraine did not need additional military assistance to help fight insurgents in the eastern part of the country but a Russian invasion would raise "a different set of questions."

Obama's comments came after NATO said Russia had massed some 20,000 troops on Ukraine's border and could use the pretext of a humanitarian mission to invade.

At a news conference at the conclusion of a U.S.-Africa summit in Washington, Obama was asked whether the United States would reconsider sending lethal aid to Ukraine.

"Well keep in mind that the Russian army is a lot bigger than the Ukrainian army. So the issue here is not whether the Ukrainian army has some additional weaponry," Obama said, noting that the separatists had not been able to match the Ukrainian army's strength so far despite causing a lot of violence.

"Now if you start seeing an invasion by Russia, that's obviously a different set of questions. We're not there yet," he said.

Obama said the United States would continue to work on a day-by-day, week-by-week basis to determine what Ukraine needed to defend itself against separatists who were backed by Moscow.

Meanwhile, U.S. and European sanctions had succeeded in hurting the Russian economy.

"The economy has ground to a halt," Obama said, noting capital flight from Russia.

"If you start seeing an invasion by Russia, that's obviously a different set of questions. We're not there yet," he said. 

Reuters