President Obama announced Wednesday that the U.S. would provide the Ukrainian government with $5 million worth of body armor, night-vision goggles and communication equipment in order to aid Kiev's ongoing fight against pro-Russian separatists in that country's east. 

Obama announced the aid after meeting with Ukraine's president-elect, Petro Poroshenko, in Warsaw. Poroshenko is due to be sworn into office this weekend. 

The White House says Obama has approved more than $23 million in security assistance to Ukraine since early March, when the situation began to deteriorate. The United States already has provided ready-to-eat meals and money for medical supplies and other non-lethal assistance, including clothing, sleeping bags and generators.

"The Ukrainian people made a wise selection in someone to lead them thru this period," Obama said of Poroshenko. The president praised the billionaire candy maker for reaching out to Ukraine's restive east and said Poroshenko's election signaled Ukrainians had rejected violence and corruption in favor of democracy.

"I have been deeply impressed by his vision, partly because of his experience as a businessman," Obama said.

At the same time, Obama warned it was critical that other nations now support Poroshenko and his new government, including by training its military and police. He urged the international community to keep up the pressure on Moscow not to support pro-Russian separatists in Ukraine.

Thanking Americans for offering support, Poroshenko said the next phase will be crucial to starting a peaceful process out of the country's political crisis.

Obama's meeting with Poroshenko came 10 days after he became Ukraine's first elected leader since its pro-Russian president fled and Moscow annexed the Crimean Peninsula, in a confrontation that's reignited old global divisions.

"He won everywhere, and clearly has been given a mandate to try to lead the country into a new era," Secretary of State John Kerry after meeting here with Poroshenko ahead of the president.

Obama was in Warsaw to help commemorate the 25th anniversary of Poland's first partially free election, an example of democratic progress that the U.S. president plans to point to in a speech later Wednesday as a model for Ukraine.

Obama was addressing a Freedom Day celebration in Royal Castle Square, remarks that the White House cast as the centerpiece of his three-country European tour and a unique opportunity to make the case directly in the region for Ukraine's solidarity.

"The president-elect of Ukraine has indicated his willingness to work with all regions of Ukraine to create a constitutional order that is representative of all people. And he has said that he is interested in pursuing good relations with Russia," Obama said the night before at a Polish Solidarity Dinner with Poroshenko. "But what he has said, and he is right to say, is that the sovereignty of Ukraine should not be sacrificed in that effort, and we fully support him in that."

The Associated Press contributed to this report.