Syria's bloody civil war has brought the country's largest number of refugees and asylum-seekers to the United States in a decade, and thousands more are expected in 2016. 

But with the influx comes mounting concerns over whether the Obama administration can properly vet them, and keep out those with terror ties seeking to exploit the system. Lawmakers are worried that not only is Syria the headquarters of the Islamic State, but that the country's state of chaos makes screening refugees that much harder. 

"I agree that the vast majority of Syrian refugees do not have ties to terror groups," Rep. Peter King, R-N.Y., who chairs the Homeland Security Counterterrorism and Intelligence Subcommittee, said at a recent hearing. "However, we have been reviewing the current security vetting procedures for a number of months, and I have a number of concerns, not the least of which is the lack of on-the-ground intelligence necessary to identify terror links." 

According to the State Department, 968 Syrian refugees have been resettled in the United States this year alone -- with the goal of bringing upwards of 2,000 in by the end of 2015. Before the start of the civil war, the number of Syrian refugees entering the U.S. each year typically was under 30. 

In addition, as of March, more than 1,500 Syrians have been granted asylum in the U.S. since the start of the war, according to the latest figures provided to FoxNews.com by the Department of Homeland Security. By contrast, the number granted asylum in 2009 was 11. 

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The difference between the two categories is asylum-seekers are fleeing specific persecution and file for protection once getting to a host country; while refugees must apply for entry and be approved in advance, typically from a refugee camp or other place outside the host country. 

The United States for decades has accepted both categories of people fleeing wretched conditions in their home countries. But the resettlement of refugees from Syria is a unique challenge. 

King noted heightened terror alerts involving ISIS recruitment and active terror plots here. "The U.S. has seen the danger of flawed refugee vetting, as well as the potential for refugees to be radicalized once they are in the U.S.," he said, pointing to the Boston Marathon bombers, Dzhokhar and Tamerlan Tsarnaev, who settled here from Dagestan and Kyrgyzstan. 

But Anne C. Richard, State Department assistant secretary of state for population, refugees, and migration, told FoxNews.com that Syrian refugees are subjected to the same enhanced screening as anyone from that part of the world. That's why it takes upwards of two years or more for adults and their families to get here once they apply. 

"It is not a fast-moving process," she said. "We have a very careful, very deliberative process." 

She notes that nearly 4 million people have fled the civil war in Syria as of March 2015. Embattled President Bashar Assad's crackdown on the Sunni population, coupled with the ruthlessness of the Islamic State, has squeezed the Syrian people and sent them to the squalor of refugee camps in neighboring countries. Currently, according to USAID, there are 1.2 million Syrian refugees in Lebanon; 1.7 million in Turkey; 727,300 in Jordan; and 246,800 in Iraq, which is still reeling from its own conflicts. 

King says Syria's "failed state" is the very reason why it's impossible to trust the screening. 

At the same June hearing, Homeland Security Committee Chairman Michael McCaul, R-Texas, noted he sent a series of letters to the White House this year warning against accelerating the acceptance of Syrian refugees. McCaul said the White House "was vague" when he asked about current screening procedures. 

"Terrorists have made it known they want to manipulate the refugee program to sneak operatives to the West," he said, using the example of two Iraqi Al Qaeda members discovered in 2009 living in Bowling Green, Ky., where they were brought as refugees. 

David Inserra, policy analyst for homeland security and cybersecurity issues at the conservative Heritage Foundation, said people have a right to be concerned. 

"Whenever you are looking at folks coming from a war-torn region and there are groups there -- whether it be IS, [Al Qaeda], al Nusra -- it can be difficult to do the background checks, to find out if they are who they say they are," he told FoxNews.com. "However, there are things we can do, and the U.S. agencies working on these cases work with various other international partners and organizations to do the proper checks. But it is a challenge."

Syrians are a tiny minority compared against the 69,909 foreigners who were resettled in the U.S. in 2013, the most recent numbers available. In that year, while only 36 Syrians were granted refugee status, 16,299 Burmese were resettled here, the largest number from any one country. Others coming from "high risk" countries with ties to terror groups included Iranians (2,579), Iraqis (19,487), and Somalis (7,608). 

Meanwhile, that year the U.S. granted asylum to 3,102 Egyptians, representing a sharp, post-Arab Spring rise -- before the 2011 revolution, the number of Egyptians granted asylum in the U.S. every year typically numbered in the hundreds. 

Advocates like the International Rescue Committee (IRC) have been urging the U.S. to accept thousands more from Syria, noting that 12.2 million are now in dire need of humanitarian assistance. The United Nations estimated last August that 191,000 had already been killed in the conflict. 

"Every day, survivors of torture, women widowed by the Syrian conflict, children traumatized by war and others tell (IRC) and other nongovernmental organizations that they think the world has given up on them," David Miliband, IRC president, wrote in an op-ed earlier this year. "The United States is in a position to help by swiftly expanding resettlement and encouraging other donor states to follow its example. The moral choice is clear." 

Richard said the program is welcoming the weakest and most vulnerable, which means female heads of households, those with medical needs, and persecuted people typically get through first. But all are subjected to layers of checks involving not only the State Department, but the FBI and the Department of Homeland Security. 

"We cannot be naïve about terror screening," Richard said. "State Department officials themselves have been the target of terrorists' threats so I don't think anyone thinks that somehow we should skip over careful screening." 

She said Congress continues to have input -- though it does not have the final say in the number of refugees or where they come from. 

At another House homeland security hearing earlier this year, FBI Assistant Director Michael Steinbach cautioned that databases are lacking information on some of these applicants, "and that's the concern." 

Richard said: "The better outcome of this would be that peace comes to Syria and people could go home, but no one predicts that anytime soon."