In this series, Newsweek maps the road to 9/11 as it happened 25 years ago, day by day.

Yesterday: Field office agents were rebuked for seeking information. "Things work much better when our agencies are communicating HQ to HQ," the CIA said.

August 23, 2001: After discovering existing intelligence that no one at the CIA had paid attention to, Margaret Gillespie, the FBI analyst detailed to the bin Laden station at the Counterterrorist Center (CTC), on August 23 requested that Khalid al-Mihdhar and Nawaf al-Hazmi be added to the Department of State's watch-list for denying visas to individuals attempting to enter the United States.

By now, U.S. Customs and the Immigration and Naturalization Service (INS) had determined that at least al-Mihdhar was still likely in the United States, and that there was no evidence that al-Hazmi had left.

The new flurry of activity prompted FBI headquarters to request that the New York and Los Angeles field offices undertake a search for the men. In a lackadaisical and non-priority computer search, the FBI's New York field office found no evidence of either. The Los Angeles field office received the search request on September 11, 2001.

The CTC requested that the State Department, Customs, and INS add Mihdhar and Hazmi to watch lists. The three existing watch lists were State's VISA/VIPER for visas, the TIPOFF system (the equivalent of today's no-fly list) and the Treasury Enforcement Communication System, an investigative tool that would prompt inspectors at airport and border entry points to delay and scrutinize travelers of interest.

Though CTC explicitly stated that the two men be watch-listed immediately and denied entry into the United States, none of this is applicable to domestic travel.

On August 24, both Hazmi and Mihdhar were entered into the three watch lists. Each was a warning of "possible travel to the U.S." On August 31, a new listing for Mihdhar was placed in an INS and Customs lookout database, describing him as "armed and dangerous."

On September 4, the State Department also used its authority to revoke al-Mihdhar's visa for his participation in terrorist activities. The next day, it entered the September 4 notice of revocation of Mihdhar's visa into the INS lookout system. State identified al-Mihdhar as a potential witness in an FBI investigation.

Though the main specific fear of an attack on July 4 had passed (not coincidentally the date that al-Mihdhar returned to the United States from Yemen, via Saudi Arabia), in late August, separate elements of the FBI possessed information about Zacarias Moussaoui; a July 10 memo from an FBI Phoenix Field Office special agent, which reported suspicions that radical Islamists were engaged in flight training in the U.S.; and the information about Khalid al-Mihdhar and of Nawaf al-Hazmi.