AMNA NAWAZ: In South Korea, a court# sentenced former President Yoon Suk## Yeol to life in prison after it found him# guilty of leading an insurrection.

While it## is a dark mark for the Congress, some argue# it's a bright spot for its young democracy.

Nick Schifrin details how a few short,# tumultuous hours challenged South Korea.

NICK SCHIFRIN: Today in Seoul, they watched# and cheered as if it were a play-by-play,## a judge making the final call in the# sentencing of former President Yoon Suk Yeol.

And after Yoon's fate was# sealed, his critics celebrated.

SONG JI-SEON, Seoul Resident (through# translator): I was watching the martial law,## which is something I'd only seen in# history books, unfold in real time.## I hoped for a harsher punishment so# that history wouldn't repeat itself.

NICK SCHIFRIN: His supporters were left shocked.

YOON KAB-KEUN, Attorney for Yoon# Suk Yeol (through translator):## Watching what appears to be a collapse of rule# of law today, I'.. we should proceed with an appeal or continue to# participate in these criminal proceedings at all.

NICK SCHIFRIN: It was December 2024 when# President Yoon declared martial law.

His## middle-of-the-night announcement sent# members of the military to Parliament.## Protesters protected the building and# their democracy, inside, the only thing## that stopped soldiers from Parliament floor,# furniture deployed by opposition staffers.

That bought time until a unanimous vote# lifted martial law.

From start to finish,## it was only six hours, but it was, and has# been, a test of South Korean democracy.

FRANK JANNUZI, President and CEO, Maureen# and Mike Mansfield Foundation: To me, the## most remarkable story is the .. democracy in the face of unprecedented challenges.

NICK SCHIFRIN: Frank Jannuzi is the president# of the Mansfield Foundation, which works on U.S.## relations with Asia.

He calls Yoon's the most# momentous domestic trial in more than 30 years## in a country that has a history of presidents# who've been impeached, jailed or overthrown.

FRANK JANNUZI: Over the last 14 months,# South Korea has emerged from this process## with due process sustained, rule of law# sustained.

Democracy itself was in the## docket in this trial.

And the South Korean# people affirmed the value of that democracy,## the resilience of that democracy,# without personalizing the crime.

NICK SCHIFRIN: The outcome for Yoon could have# been much worse.

The prosecution asked for the## death penalty.

And it wasn't only Yoon.

Five# other former officials were also convicted,## including the former defense minister, who# will spend the next 30 years in prison.

Current President Lee Jae Myung,## Yoon's longtime rival, has reframed from# politicizing the trial, says Jannuzi.

FRANK JANNUZI: This allowed him to cool down the# temperature a bit and also allowed him to focus## really on where he needed to focus, which was his# foreign policy priorities, sustaining an outreach## to Japan and reassuring the United States that# South Korea would be a loyal, faithful ally.

NICK SCHIFRIN: Over the past year,# South Korea's faced pressure over## trade and promised to increase defense# spending.

It's been a balancing act## for a democracy that has now sent a# former president to prison for life.

For the "PBS News Hour," I'm Nick Schifrin.