On Friday, President Barack Obama called sweeping federal computer and phone surveillance programs “modest encroachments on the privacy” of Americans.

Modest?

That’s a mighty mild word for the wide-ranging seizure of the private electronic communications of many millions of Americans.

And while last week’s news about the stunning scope of that surveillance by the National Security Agency and FBI has stirred considerable debate, there’s no disputing this 21st century reality:

Over the last decade, Washington has vastly — not modestly — increased its power to snoop on the U.S. public.

There’s a strong case to be made that an elevated “encroachment on” privacy is necessary in an age of global terror that is also an age of nuclear weapons.

That’s what Congress had in mind when it passed, at President George W. Bush’s urging, the Patriot Act in 2001, and when it reauthorized the law, at President Obama’s urging, in 2011.

Yet there’s a strong case, too, for thoroughly reviewing those surveillance programs — and for providing oversight that goes beyond secret judicial orders and periodic notifications of remarkably compliant congressional leaders.

Indeed, many prominent federal lawmakers from both parties have rushed to defend the surveillance initiatives since the blockbuster news about them leaked last week.

Senate Intelligence Committee Chair Dianne Feinstein, D-Calif., told ABC’s “This Week” on Sunday: “The only thing taken, as has been correctly expressed, is not content of a conversation, but the information that is generally on your telephone bill, which has been held not to be private personal property by the Supreme Court.”

Sen. Feinstein cited, as examples of the surveillance’s life-saving benefits, two declassified cases where the phone-records seizures foiled terror plots — one against a hotel in Mumbai, India, the other against New York City’s subways.

Sen. John McCain, R-Ariz., sounded a similar theme Sunday on CNN’s “State of the Union,” explaining: “I do believe that if this was September 12th, 2001, we might not be having the argument that we are having today.”

But this isn’t Sept. 12, 2001.

This is June 11, 2013.

And Sen. McCain did concede that “perhaps there has been some overreach” in the surveillance programs.

Certainly it’s an overreach to expect Americans to blindly accept Big Brother’s intensifying intrusions. Still fresh in the public mind are the Internal Revenue Service’s chilling targeting of conservative groups and the Justice Department’s wiretapping of journalists on an unprecedented scale.

House Homeland Security Committee Chair Michael McCaul, R-Texas, said Sunday on CBS’ “Face the Nation” that he believes the electronic surveillance is not only “lawful,” but helpful in the U.S. counter-terrorism effort.

However, Rep. McCaul accurately added: “The optics are terrible in this case when you consider the recent scandals. You have to ask yourself this question: Can you trust this administration with your phone records?”

You also have to ask yourself, regardless of whether you trust this or that administration, what about future administrations?

Once this comprehensive spying apparatus has been created to track our computer and phone records, to what nefarious uses could it be put in the decades to come?

The powers that be in Washington must clearly spell out the limits, assuming there are any, on their legal prerogatives to monitor private individuals and businesses.

And that defining mission transcends the ongoing controversy — criminal leaker or brave whistle-blower? — about the young man who revealed the staggering extent of the surveillance system.

Because when government encroaches upon Americans’ fundamental freedoms, there’s nothing “modest” about it.