Secretary of State John Kerry says the United States is committed to increasing the number of refugees it is willing to take in as U.S. allies in Europe struggle to accommodate tens of thousands of refugees from the Middle East and Africa. 

After closed-door meetings on Capitol Hill Wednesday, Kerry said President Obama has made it clear that the U.S. wants to take a leadership role on humanitarian issues. 

"We are looking hard at the number that we can specifically manage with respect to the crisis in Syria and Europe," he said. "That's being vetted fully right now." 

Kerry met with members of the House and Senate Judiciary committees. He did not give any specifics on the number of additional refugees the U.S. may be willing to take. 

The U.S. has vowed to help its European allies with an escalating crisis. Earlier this week, Democratic presidential candidate Hillary Rodham Clinton, Kerry's predecessor, called for a "concerted global effort" to assist the refugees. 

White House press secretary Josh Earnest said Tuesday that the Obama administration has been looking at a "range of approaches" for assisting U.S. allies with 340,000 people freshly arrived from the Middle East, Africa and Asia. Many are fleeing parts of Iraq that are under the Islamic State group's control. 

While Germany braces for some 800,000 asylum seekers this year, the U.S. hasn't said if it will increase its worldwide quota for resettling refugees from 70,000. Only a fraction of those would be Syrians, who must first navigate a multiyear application process before learning if they can start a new life in the United States. Kerry's briefings will also canvass migrant exoduses from Central America and elsewhere. 

The U.S. resettlement process for refugees, as it stands, is slow. They can wait around three years to find out if they can move to the United States, meaning Washington wouldn't be able to offer Europe much in quick assistance. Throughout Syria's 4 1/2-year civil war, the U.S. has accepted only about 1,500 Syrians -- a tiny percentage of the 11.6 million people who have been chased out of the country or uprooted from their homes. 

After the fall of Saigon in 1975, the U.S. accepted more than a million refugees from Vietnam, Cambodia and Laos. In 1999, tens of thousands of mostly Muslim Kosovar Albanians were flown to the U.S., processed at Fort Dix in New Jersey and ultimately resettled. During the Iraq war, more than 50,000 refugees were allowed to come under a special, expedited program for people whose religious beliefs or past work for the U.S. military put their lives at risk. 

But what those crises involved and Syria's may lack is a sense of U.S. responsibility. Refugee operations in Southeast Asia followed years of U.S. warfare there, as did the decision to take in tens of thousands of Iraqis over the last decade. Many Americans will feel differently about taking large numbers of Syrians displaced by a war that the United States has tried hard to avoid. 

Asked directly if the Obama administration felt responsible to share Europe's refugee burden, Earnest stressed U.S. support thus far: $4 billion in humanitarian aid, more than any other country has provided, and ongoing diplomatic work to resolve Syria's conflict peacefully. The diplomacy appears nowhere near ending violence that started in 2011 with a government crackdown on political opponents, spawning an armed insurgency and eventually leading to Islamic State extremists seizing much of the country. 

Security concerns also run high, especially after two Iraqi refugees were arrested in Kentucky four years ago on charges they plotted to help kill American troops in Iraq. U.S. officials appeared to miss several security warnings. Lawmakers and presidential candidates have cited the case in opposing more Syrian refugees in the U.S.