This month, as officials in the Obama administration trumpet new warnings about "credible" threats to the United States homeland, the long-ignored role of America's primary terror alert system is under serious scrutiny for the first time.

The National Terrorism Advisory System (NTAS), a function of the massive Department of Homeland Security, didn't issue any public advisories this summer as Western passport holders took up jihad in Syria by the thousands and anti-American extremists carved out safe havens in Iraq. In fact, NTAS, the successor to the George W. Bush administration's color-coded Homeland Security Advisory System, has been silent for longer than most realize.

Since replacing the old system in 2011, it has not issued a single alert, bulletin or advisory to the American public. NTAS encourages Americans to check its website and social media feeds for "information about threats in specific places or for individuals exhibiting certain types of suspicious activity." But no alert has ever been posted to the website, the Twitter account has never tweeted, and the Facebook page is empty. 

"Something has been replaced with nothing," said Michael O'Hanlon, a national security expert at the Brookings Institution. "Whether the Bush model was bad enough that this represents a net improvement can be debated. However, it does feel like the government still hasn't figured out how to communicate with citizens about possible dangers, or the need for vigilance."

DHS officials insist that their terror alert system is working adequately.

"DHS will continue to monitor intelligence reporting and respond appropriately to protect the American people from an ever-evolving threat picture, and, as always, encourage the public and our partners in law enforcement and the private sector to remain vigilant in promptly reporting any suspicious activities," DHS spokesman S.Y. Lee told Foreign Policy.

But the dramatic pendulum swing — from an Orwellian Bush-era alert system that inundated the public with vague warnings to an Obama-era system of radio silence — has only just begun befuddling lawmakers responsible for overseeing the federal agency.

"I am deeply concerned about this problem and the fact that no alerts have been issued despite all the imminent threats we face," Rep. Tom Marino (R-Penn.) told FP. "I am currently working closely with my colleagues on the Homeland Security Committee to plan more congressional inquiries into the utilizations and usefulness of the current NTAS."

In 2011 when the Obama administration discarded the color-coded system, Janet Napolitano, then Homeland Security secretary, said the system had "faded in utility except for late-night comics."

But when the new system was introduced, the promise to the public was a more discerning alert system, not an invisible one.

NTAS would "provide the American public with information about credible threats so that they can better protect themselves, their families, and their communities," Napolitano said when she unveiled the system. 

The new program dropped the five-colored ranking with a simpler, two-tiered system. For the most serious warnings, NTAS would issue an "Imminent Threat Alert," triggered in the event of a "credible, specific, and impending terrorist threat against the United States." The lesser warning is called an "Elevated Threat Alert," which would not include any details on timing or terrorist targets.

The government hasn't issued a warning of either type, even as the United States has faced elaborate bomb plots from al Qaeda in the Arabian Peninsula, lone-wolf attacks directed at the Boston Marathon and other soft targets, and plotting from an obscure al Qaeda cell in Syria known as the Khorasan group, which the Pentagon countered with airstrikes just last week. In August, Britain raised its level of threat from international terrorism from substantial to severe, meaning an attack is "highly likely."

"For all its flaws, the Bush system at least kept people thinking about possible threats," O'Hanlon said.

The NTAS's curious silence was pointed out in a little-noticed Sept. 15 report from the Intelligence and National Security Alliance, a public-private organization of national security experts. "It is particularly advisable to review whether the narrow focus on counterterrorism and the high threshold for issuance makes the NTAS an ineffective tool for communicating useful information to the public," the report stated.

The White House referred all questions to DHS. 

In an effort to explain the NTAS's silence over the past three years, a DHS official emphasized the strict criteria the department uses to justify the issuance of an alert.

"We only issue out alerts when we have specific or credible information to convey to the American public," said one DHS official, speaking on condition of anonymity.

Another department official emphasized that NTAS alerts are reserved for instances where specific, localized information can be provided to the public instead of generic, all-purpose warnings. "It may include specific information, if available, about the nature of the threat, including the geographic region, mode of transportation, or critical infrastructure potentially affected by the threat, as well as steps that individuals and communities can take to protect themselves and help prevent, mitigate or respond to the threat," the official said.

Neither official conceded that NTAS's inactivity suggests the system is flawed or obsolete.

However, one official noted that other offices in the department do play a role in warning the public. "[NTAS] is not the only manner in which we communicate. I can send you eight statements that the secretary himself has issued out on different threats," said the official, referring to Homeland Security Secretary Jeh Johnson.

To be sure, there is little nostalgia for the Bush-era system, established shortly after the terrorist attacks of Sept. 11, 2001. That system, which rarely adjusted the threat level from the middle setting of yellow ("significant risk of terrorist attacks") became a symbol of post-9/11 hysteria and security theater.

"After 9/11, officials found that general warnings did not provide enough detail to guide behavior and, if they were maintained long enough, simply became background noise," said Daniel Byman, a professor in security studies at Georgetown University. "They did little to inform the public of the nuances of the threat."

Beyond that, some critics held that the Bush administration manipulated the system to stoke fear in the hearts of Americans at politically advantageous times. On the eve of the 2004 presidential election, for instance, then-Homeland Security Secretary Tom Ridge later revealed that he was pressured by then-Defense Secretary Donald Rumsfeld and then-Attorney General John Ashcroft to raise the terror threat level. "After that episode, I knew I had to follow through with my plans to leave the federal government for the private sector," he wrote in his memoir. The Bush administration denied the allegation.

Byman noted that the lack of alerts from NTAS is likely the result of lessons learned after a decade of confusing and vague terror warnings. "The threat warning system was put in place after 9/11 with two assumptions," said Byman.

The first assumption, held by many counterterrorism experts, was that the threat of another attack on the homeland was incredibly high. "Although there have been plots and several attacks, notably the Boston marathon bombings, the overall danger is far less than what was anticipated in the aftermath of 9/11," he said. "Second, the public anger at the government after 9/11 was in part a reflection of a sense that some officials were 'in the know' but that this knowledge was not shared with the public."

While both those concerns have been somewhat allayed in recent years, NTAS's silence remains unsettling to overseers on Capitol Hill. "We need a complete infrastructure of notifications systems and the president needs to regularly inquire with his security commission about the effectiveness of it," Marino added. "The underutilization of the NTAS seems to demonstrate the ineffectiveness of the president's ability to directly communicate with our citizens about terror threats."

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