Long after the last U.S. soldier left Iraq, thousands of Iraqis who worked for our military and civilians are still living in dangerous limbo, waiting for promised U.S. visas that haven't arrived.

Radical Shiite militias are threatening to kill these Iraqis because they helped Americans. I just learned of one case in which a medical syringe and a jar of concentrated sulfuric acid were left at the Baghdad door of a former Iraqi interpreter for U.S. forces. The accompanying note said the man's face and body would soon be washed with the acid.

Even if this man had the funds to flee Iraq (which he doesn't), he and his family are stuck there: The U.S. Embassy has been holding their passports for the last year for visa processing, as the process drags on and on and on.

The blockage is due in large part to new security checks instituted in 2009 after two Iraqi refugees in Kentucky (who never worked for U.S. forces) were accused of plotting to help terrorists.

Top U.S. officials say they are working hard to speed up the visa process and are nearing a breakthrough. But, although the numbers show a slight uptick, they've still barely budged.

Vice President Biden's top national security adviser, Antony Blinken, recently told me after a talk at the Center for American Progress, a Washington think tank: "We owe these people. We have a debt to these people. They put their lives on the line for the United States."

Blinken said that, over the last two to three months, he and his colleagues, led by deputy national security adviser Denis McDonough and counterterrorism adviser John Brennan, have spent "literally hours in the windowless situation room with all the agencies, working through [the Iraq visa] problem.

"What I can tell you today is I think we have now a way forward that will show demonstrable progress in bringing more people into the United States while making sure our security is upheld," Blinken said.

No doubt he and his colleagues are sincere in their efforts, but the numbers are still stuck.

Consider this: In 2008, Congress mandated 25,000 special immigrant visas (known as SIVs) for Iraqis who helped us over a period of five years; fewer than 4,500 have been issued. According to State Department figures, 719 were granted in fiscal 2011 and 569 during the first six months of fiscal 2012. No breakthrough yet.

"The SIV program has not delivered," says Bob Carey, vice president for resettlement policy at the International Rescue Committee. "There is an enormous backlog of people whose lives are at risk."

Indeed, the number of desperate applicants remains in the thousands. Many Iraqis who helped Americans have chosen to apply for U.S. visas through another special refugee program. As of last July, there were 39,000 Iraqis on that waiting list. In the first six months of fiscal 2012, only 2,500 were admitted.

And most applicants have been waiting one to three years.

So what's gone wrong? Why can't we meet our moral obligation to Iraqis who risked their lives to help us?

My answer: We have a security bureaucracy that's gone bonkers. In the post-9/11 era, under the Department of Homeland Security, we've set up so many overlapping layers and redundancies that it's almost impossible to navigate the system. "One agency doesn't necessarily recognize another's security checks," says Carey. "Often one check will expire before the next is completed."

Take the case of A.M., who worked for the U.S. Army from 2009-11. He's been waiting more than a year for his security clearance. Because of the wait, his U.S. Embassy-required medical exam "expired" and he had to take it again, paying another $400. Meanwhile, he is living in hiding, under death threat, afraid even to visit his wife and year-old daughter.

"I risked my life to help the U.S. Army and now you are selling me to the terrorist why?" he e-mailed me. "We just want the U.S. government to help us like they promised."

Or take A.L., who has been waiting for more than three years, took his medical exam three times, and fingerprints twice. The embassy gave him a date of a year ago, on which he was supposed to travel, but on that day he was told more security checks were needed. He had sold his business and his car, and is running out of money.

"We are threatened with death every moment," he wrote me. "Is this what we deserve because we worked with U.S. forces. Please. Please. Help us."

That will require the White House to tame the Kafkaesque Homeland Security bureaucracy, something that still hasn't happened and probably needs presidential intervention. In the meantime, thousands of Iraqis suffer in limbo and America's credibility takes a further beating.

"If we don't [move on this], it will have a chilling effect on the willingness of people around the world to work with our missions," Blinken admitted.

He's so right.

E-mail Trudy Rubin at trubin@phillynews.com.

To help Iraqis who helped us, visit netroots.thelistproject.org