WASHINGTON, Sept. 18  -- U.S. President Barack Obama on Thursday pledged continued efforts to seek a diplomatic solution to the Ukraine crisis.

"In addition to the concrete expressions of support through security assistance and economic assistance, we are going to continue to help to mobilize the international community towards a diplomatic solution," the president told reporters after meeting with his Ukrainian counterpart Petro Poroshenko at the White House.

He praised the Ukrainian leader for his efforts to broker a ceasefire in eastern Ukraine and pass legislation offering more autonomy to the regions there.

"Those were not easy laws that President Poroshenko passed, but I think they indicated his commitment to an inclusive Ukraine, his commitment to a Ukraine that has decentralization and empowers local communities," Obama said.

"I have great confidence that President Poroshenko is balancing a lot of different variables here in a very difficult situation, but he's the right man for the job," he added.

Poroshenko, who was elected president in May, is on his first visit to the United States. He appealed on Thursday morning to U. S. Congress for lethal aid.

"Blankets, night vision goggles are also important, but one cannot win the war with blankets," he told a joint session of U.S. Congress. "Even more, we cannot keep the peace with a blanket."

The White House announced 46 million dollars in new security aid for Ukraine's military and border guards including counter- mortar radars, but did not meet Poroshenko's demand for lethal weaponry.

"It's simply the judgment of the president that the best way for us to resolve, or for the situation in Ukraine to be resolved is through negotiations between the Ukrainian central government and the Russian-backed separatists in the east," White House spokesman Josh Earnest said of Obama's refusal to provide Kiev with heavy weapons.

Poroshenko told reporters at the White House that he was satisfied with the assistance being provided by Washington.

"The only way we can de-escalate the situation in the eastern part of our country is the peace process," he said, adding "We really hope that the ceasefire, which already lasted for 12 days, will transform into a real peace."