President Obama and Ukrainian President Petro Poroshenko met in the White House Thursday to discuss America's role in the escalating crisis in Ukraine. 

Earlier in the day, the new leader of the embattled former Soviet republic pleaded for U.S. military aid in a high-profile address to Congress, saying that while nonlethal aid like blankets and night-vision goggles is important, "one cannot win the war with blankets.”

To the backdrop of Poroshenko's pointed remarks, the Obama administration announced $46 million in new security assistance to Ukraine's military. The package, though, stops short of fulfilling the urgent request from Poroshenko for lethal aid to help his country fight against Russian-backed separatists. 

“You have a strong friend not only in me personally but as you saw in Congress, have strong bipartisan support,” Obama said following the meeting. “The people of America stand with the people of Ukraine.”

The announcement underscored the divide between Ukraine's appeals and the willingness of the Obama administration to more deeply engage in that conflict. While the U.S. has previously given Poroshenko’s government nearly $60 million in nonlethal aid, Obama has resisted Ukraine’s request for lethal assistance. 

Speaking before Congress, Poroshenko nevertheless thanked lawmakers for their support of Kiev in its fight against Russian-backed separatists and said freedom “is at the core of Ukrainian existence.”

"We have an unbreakable will to live free," he said, saying his nation was "at the center of the most heroic story of the last decade." 

He said that battle urgently requires "both lethal and nonlethal" assistance. 

"I urge America to help us. And to rise and to be equal to its natural and manifest role. I urge America to lead the way," he said, to applause. 

Global nuclear non-proliferation, the future of the NATO alliance and peace in Europe are all on the line, Poroshenko told lawmakers. He also called Russia's annexation of Crimea a "most cynical act of treachery.” 

Ukraine and the separatists are battling for control of eastern Ukrainian cities on Russia's border. The Ukrainian parliament passed a law granting the rebel strongholds greater autonomy, but rebel leaders insist on full independence from Ukraine.

Poroshenko compared Ukraine’s right to defend its territory to that of Israel and said the world was on the eve of another cold war.

“The war that these young men and women are fighting today is not only Ukraine’s war. It’s Europe’s and it’s America’s war too. It’s a war of the free world and for the free world.”

Obama is scheduled to meet with Poroshenko in the Oval Office Thursday.

White House officials made clear that Poroshenko's visit -- his first to the U.S. since being elected this summer -- was aimed in part at sending a message to Russia about the West's backing for the embattled former Soviet republic.

"The picture of President Poroshenko sitting in the Oval Office will be worth at least a thousand words -- both in English and Russian," White House spokesman Josh Earnest said.

Ukraine and Kremlin-backed separatists have been locked in a monthslong fight for control of eastern Ukrainian cities that sit on Russia's border, aggression that followed Russia's annexation of the strategically important Crimean Peninsula. The U.S. and Western allies have condemned Russia's provocations, levying a series of economic sanctions and restricting President Vladimir Putin's involvement in some international organizations.

But the penalties have done little to shift Putin's calculus. In recent weeks, the West has accused Russia of moving troops and equipment across its border with Ukraine, though the Kremlin denies such involvement.

Ukraine and the Russian-backed separatists inked a cease-fire agreement Sept. 5, though the deal has been violated repeatedly. On Wednesday, shelling in rebel-held parts of the east killed at least 12 civilians, as a top leader of pro-Russian rebels rejected Ukrainian legislation meant to end the unrest by granting self-rule to large swaths of the east.

Poroshenko, a billionaire businessman, won Ukraine's presidential election in May after his country's Russian-backed leader fled amid popular protests. Western leaders have praised Poroshenko's commitment to reform, and Obama will press him Thursday for more aggressive political and economic actions that can stabilize the fragile nation.

At the heart of the conflict between Ukraine and Russia is the former Soviet republic's desire to strengthen ties with Europe. Poroshenko has only deepened those efforts, making a high-profile appearance at the NATO summit this month and overseeing the backing of a deal this week to strengthen economic and political ties with Europe.

The deal lowers trade tariffs between Europe and Ukraine, requires Ukrainian goods to meet European regulatory standards and forces the Kiev government to undertake major political and economic reforms.

Following a vote by Ukrainian lawmakers, Poroshenko called the deal "a first but very decisive step" toward bringing Ukraine fully into the European Union.

The Associated Press contributed to this report.