Sen. Dianne Feinstein, D-Calif.

The National Security Agency (NSA) program based on section 215 of the USA Patriot Act, which collects phone numbers and related data, is often called a “surveillance program” or a program to “listen to phone calls.”

It is neither.

Rather, this program collects only phone numbers and the duration and times that calls are made.

When the NSA learns of a number used by a terrorist connected to al-Qaeda, it can search its database of phone records.

Only 22 highly vetted NSA analysts can approve a query of this database — and only when they have a reasonable, articulable suspicion that the number is connected to terrorism.

If the NSA analyst believes that circumstances justify the need to know the actual content of the call to probe further into what may be an active terrorist plot, the numbers are sent to the FBI, which requests a warrant from the court that oversees the Foreign Intelligence Surveillance Act (FISA). Ultimately, this court determines if “probable cause” is sufficient to grant the warrant to collect the content of the call.

The NSA recently disclosed that 54 terrorist “events” have been interrupted in part because of information gleaned from this program and another recently declassified NSA program, called PRISM, based on Section 702 of FISA.

In addition, the NSA call-records program is reviewed and authorized every 90 days by the FISA court. It is interesting that Edward Snowden leaked the court order reauthorizing the program but did not provide the corollary order containing the program’s many strictures.

Information obtained through this program helped lead to the arrest and life sentence of Adis Medunjanin, a co-conspirator of Najibullah Zazi, who was planning to attack the New York subway in 2009 — one of the most serious terrorist plots in the United States since Sept. 11. Zazi and another co-conspirator are awaiting sentencing, but both face life in prison.

Balancing privacy rights with our nation’s security is difficult to achieve, but I know of no federal program for which audits, congressional oversight and scrutiny by the Justice Department, the intelligence community and the courts are stronger or more sustained.

I read enough intelligence on terrorists to know that if they can, they will attack us.

New bombs and techniques are in the making. The Transportation Security Administration remains on alert. So should every citizen.

Despite these real threats that our intelligence programs seek to thwart, I intend to work with members of the Senate intelligence and judiciary committees to consider changes to the NSA call-records program in an effort to increase transparency and improve privacy protections. These changes would require that:

* the number of Americans’ phone numbers submitted as queries of the NSA database be made public annually, as well as the number of referrals made to the FBI each year based on those queries;

* the number of warrants obtained by the FBI — based on probable cause — to collect the content of any call be released annually;

* the number of times in a year that any company is required to provide data pursuant to FISA’s business records provision be released;

* all classified FISA court opinions and reports on U.S. persons targeted for surveillance under FISA be made available in a secure location to every member of Congress ;

* the five-year retention period of phone records be reduced to two or three years;

* the ideological diversity of the FISA court be increased (86 percent of judges appointed to the court by Chief Justice John G. Roberts Jr. have been Republicans and the vast majority were prosecutors, according to media reports); and

* the FISA court review each query of the database as soon as practicable to determine its propriety under the law.

In addition, the congressional intelligence committees should periodically review all intelligence data-collection programs involving Americans to ensure that the Justice Department guidelines required by Executive Order 12333 are adequate and are followed.

The bottom line is that actionable intelligence is the best way to prevent an attack against our country.

The NSA call records program is a case in point. In conjunction with other programs, such as PRISM, it has contributed to the disruption of terrorist plots and done so within a legal framework that provides strong privacy protections, court review and congressional oversight. I believe it is vital and necessary in protecting our country from future attack. It must be sustained.

U.S. Sen. Dianne Feinstein, D-Calif., chairs the Senate Intelligence Committee. Her commentary originally appeared in The Washington Post.