With an end-of-year deadline looming to re-authorize a vital foreign intelligence collection tool, senior U.S. government officials said Monday that the program had 106,000 foreign targets in calendar-year 2016 – as they urged renewal, arguing there is “no substitute” for this kind of intelligence.

The “702” program – Section 702 of the Foreign Intelligence Surveillance Act (FISA) -- is "the single most important operational statute," one senior government official said, pointing to its effectiveness aiding counter-proliferation efforts, disrupting terrorism plots and aiding warriors on the battlefield.

Officials authorized to speak on behalf of their department or agency briefed reporters Monday. As part of the briefing, Director of National Intelligence Dan Coats said its reauthorization is "absolutely a top priority," adding the intelligence community wanted to be "upfront with the American people" about the program, which is only used against foreign targets.

Senior U.S. government officials say the tool was instrumental in fleshing out the ISIS network associated with Shawn Parson, who was a recruiter and prolific propagandist who directed sympathizers to launch attacks against western targets. He was killed in Syria in 2015.

The U.S. officials also said intelligence from the program helped Turkish authorities identify the assailant in an Istanbul New Year's attack, which killed 39 people.

Lawmakers from both parties have expressed their concerns about U.S. citizen information and the safeguards to protect it, as well as whether officials from the Obama White House wrongly leaked the intelligence to damage the incoming Trump team.

A senior NSA analyst, whose father was on the ground at the World Trade Center after 9/11 and now suffers serious health issues, emphasized the ripple effect of terrorist acts -- saying there are multiple protections in place to maintain U.S. government commitments to privacy, as well as the integrity of the data.

The analyst said the ability to search foreign intelligence in the database already gathered under 702 cannot be underestimated, citing its utility when an American is taken hostage overseas or a terror suspect is apprehended. The analyst said the intelligence community uses this resource to flesh out their network of contacts, based on so-called “pocket litter” -- which is intel-speak for telephone numbers or emails found on a suspect. The analyst said it is especially helpful to determine if there is an American connection to an overseas cell or plot.

Sen. Ron Wyden, D-Ore., among others, has pressed the NSA to make available the number of Americans who have been swept up during surveillance of foreign targets, or so-called "incidental collection." A senior U.S. government official said the figure is "unknowable," because so much of the data is only fragmentary.

While the senior government officials said they have "full confidence" 702 will be re-authorized, they hope it will be on a permanent basis, adding that any tweaks to the existing legislation to enhance civil liberties protections for Americans should not end up protecting foreign targets or blocking information-sharing among U.S. government agencies.

Coats said discussions with Congress continue.