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Texas lawmakers say they are deeply concerned that the federal government lost track of 17 Afghan military personnel who went AWOL from Lackland Air Force Base, where they were studying English.

U.S. Sens. John Cornyn and Kay Bailey Hutchison, and House Judiciary Committee Ranking Member Lamar Smith, all Republicans, are demanding answers from the U.S. Air Force and the Department of Homeland Security on what Cornyn described as a "breach of national security." And the lawmakers are asking why the alert was issued only last week when the men started disappearing 18 months ago.

Smith, who serves on the House Homeland Security Committee, is demanding that Air Force and Homeland Security officials brief Congress on the Afghans' disappearance.

“It is extremely troubling that these Afghan military members with special access to U.S. military facilities were allowed to disappear," he told FoxNews.com in a statement Monday. "This is an unacceptable threat to American communities and members of the military, who live and work on the base, that these AWOL military members can still attempt to access.

“We need to ensure there is a system in place so foreign military officers training in the U.S. can’t go AWOL. We must protect the safety of our citizens, and the members of the U.S. military who defend us every day.”

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Hutchison said she, too, was troubled that the Afghans had walked off the base and disappeared.

“I’m deeply concerned about the national security implications of these missing international military trainees and what is being done to find them," she said in an e-mail statement to FoxNews.com.

"It is disturbing the Air Force has not made greater efforts to bring this matter to light. It is important for the Defense Department to work with other law enforcement agencies to find these individuals and to prevent this from happening again.”

On Friday, Cornyn demanded answers in a letter to Air Force Secretary Michael B. Donley, calling the defection of 17 Afghan military members over the course of 18 months a breach of national security.

“My office has never received official notification from the Department of the Air Force regarding this potential national security threat, which could pose a danger to citizens in Texas and elsewhere in the country," Cornyn wrote.

FoxNews.com reported exclusively on Thursday that a nationwide alert had been issued for 17 members of the Afghan military who went AWOL over an 18-month period from the Defense Language Institute at Lackland Air Force Base in Texas.

The Be-On-the-Lookout bulletin was compiled by Naval Criminal Investigative Service on June 9.  The bulletin included photos of all 17 men and was distributed widely to local, state and federal law enforcement agencies as recently as the evening of June 16. 

On Friday, federal officials announced that seven of the missing had been located, leaving 10 who remain at large.

Sources said that as of November 2009, one of the deserters was in Canada, one is now a lawful permanent resident in the U.S., one has left the country and another four are in federal custody and in removal proceedings. The other 10 remain unaccounted for.

But congressional sources briefed by DHS on Friday afternoon said they were told 11 men remain at large.

It remains unclear why different federal agencies have provided conflicting accounts of the whereabouts of the 17 missing men.  It’s also unclear why the alert was sent out for 17 Afghans after the whereabouts of six or seven of them were already known.

Sources confirmed to FoxNews.com on Monday that four Afghans named as missing in the nationwide alert had been detained before the NCIS report was written on June 9.

On Monday morning, Cornyn’s office passed along the Air Force’s response from Lt. Col. Jeffry W. Glen, Air Force spokesman:

“The Air Force has received Sen. Cornyn’s letter and will respond to the senator’s questions directly. With regard to the missing Defense Language Institute students, we monitor these cases and have been working with DLI, the Department of Homeland Security, Department of State and other agencies to ensure a comprehensive approach.  When the Defense Department learns an international student has gone missing, DHS Immigration and Customs Enforcement is immediately notified and appropriate action is taken.”