"Specifically, the president's policy has called for an end to chain migration", she said.
He added that the suspect had entered the country through "extended-family chain migration", a system the president is seeking to end that allows families to sponsor relatives to come to the United States.
"The problems with the Visa Lottery are various", Cissna said.
"DHS can confirm that the suspect was admitted to the United States after presenting a passport displaying an F43 family immigrant visa in 2011".
"Today's terror suspect entered our country through extended-family chain migration, which is incompatible with national security", the president declared.
But when pressed to explain the connection to terrorism from the White House podium on Tuesday, Director of US Citizenship and Immigration Services Lee Francis Cissna could cite olnly hypothetical risk. First, it can just as easily be made in reverse - without such legal immigration, the US would be denied the rewards extending from the 9.3 million people who entered the USA legally between 2005 and 2015 on family ties, or about 70 percent of the legal immigration during that decade.
Ullah said that he had carried out the attack in retaliation for USA airstrikes on Islamic State in Iraq and Syria (ISIS) targets in Syria and elsewhere, and said that he chose the subway passageway because of its Christmas-themed posters.
Blackburn stressed that not only is it important to look at the immigration system, but it's also vital to be aware of the associations and affiliations that immigrants may have.
"It's worse than not effective, it's counterproductive", said Michael Breen, president and CEO of the Truman Center and Truman National Security Project, whose membership includes former national security officials and veterans of the Obama and Clinton administrations. And chain migration candidates are still screened, so if there are national security threats among them, they may have become so after arriving.
As Breitbart News reported, Ullah was able to enter the U.S.as the nephew of a man who had previously won a Green Card on the Diversity Visa Lottery, which doles out 50,000 visas to foreign nationals from a multitude of countries, including those with known terrorist problems. It is time for Congress to prioritize the interests and safety of American citizens.