GEOFF BENNETT: With thousands already dead, we're only days into what could be a cauldron of ever-increasing violence between Israel and Hamas.

John Yang gets perspectives now from two experienced leaders and observers in Israel and the West Bank.

JOHN YANG: Geoff, in its 75 years of existence, Israel had never seen anything like the brutal attack by Hamas on Southern Israel, Israel's 9/11.

And now Israel is poised for a military operation in Gaza that Prime Minister Benjamin Netanyahu has vowed will exact a price that Israel's enemies will remember for decades to come.

We get two views on these historic events.

First, Yohanan Plesner, who is the president of the Israel Democracy Institute and a former member of the Knesset, the Israeli legislature.

Mr. Plesner, first of all, thank you very much for being here.

Why did Hamas act?

What was their -- what did they try to accomplish and why did they do it now?

YOHANAN PLESNER, President, Israel Democracy Institute: Well, those are two questions.

It reminds me of the question after 9/11.

So many Americans asked, but why did they do it?

Why did they do it?

And the answer is very similar.

Hamas is a terrorist jihadist organization with ISIS-like tactics and state-like capabilities and an ideology, a strong ideology, that calls for the annihilation of the state of Israel.

It's both an ideology and an operational plan, annihilating the Jewish state and killing all Jews.

And, in this respect, nothing changed for 30 years.

It was building up capacity, building up capability, looking for the right moment.

And, in fact, in 2014, there was an attempt by Hamas to launch the exact same thing.

Just, this time, the Hamas terrorists tried to infiltrate through tunnels, rather than in the way they did it this time, and they just failed.

The IDF intercepted their attempt.

This time, as a result of an intelligence failure and an operational failure, the IDF was not able to intercept this operation.

And we ended up with this catastrophe.

And, as a matter of fact, from their vantage point, it's just a minimalistic outcome.

They had many more -- much more ammunition, hand grenades, side bombs.

They were ready to kill way more babies, to conduct way more atrocities, to rape way more women, and it's -- rape way more women.

And it's the bravery of those soldiers and civilians that blocked them that saved us from even a greater catastrophe.

JOHN YANG: You mentioned an intelligence and operational failure.

Do you think Israel was distracted by the domestic politics?

Do you think that they had felt that Hamas was bottled up in Gaza?

What do you think happened?

YOHANAN PLESNER: Well, the fact that Israel was deeply immersed in an internal debate around the nature of our democracy might have -- again, I don't have the intel, but I do have impressions, and we did have some evidence over the time -- might have given them the idea that Israel is now in a weak spot, and it's an opportunity for them to attack.

But they don't really need an excuse or motivation, and this also leads us to what should be the outcome of this entire event.

Hamas, as long as it controls state-like capabilities, will continue to try, strive to destroy and kill all Jews.

And it's just less than a mile away from our communities.

So there's no option.

It's -- they introduce us a choice of a zero-sum game.

It's us or them.

And, obviously, it will be us.

And this, the Hamas capabilities, Hamas leadership, Hamas operatives, all of them need to be obliterated.

They need to be crushed.

They need to be dismantled.

And, of course, it's very hard, it's very difficult, because they perpetrate double war crimes.

They both target civilians, but they situate their capabilities within the civilian population.

They use their population as human shields.

You won't be surprised if I will tell you that they situate their capabilities in mosques, in hospitals, in schools, in residential buildings.

And, therefore, to dismantle Hamas capability, which is not only an Israeli interest, as a matter of fact, imperative, but it's in the interest of the entire free world, because Hamas is an Iranian ally.

It's a Hezbollah ally.

They want to dominate the entire region with their murderous ideology, and obviously to gain control of the region's resources.

And that would be a disaster for the entire world and, of course, for the free world.

So we -- only one outcome can come out of it, dismantling Hamas.

And it will be long.

It will be painful.

And, unfortunately, there will be a dear price in lives, in Israeli lives and also in Palestinian lives, not only of Hamas operatives, which, obviously, I'm not very sad about it, but Palestinian civilians as well.

Unless they manage and work towards detaching themselves of Hamas capabilities, there will be tragic civilian casualties as well.

And we have to understand it.

But, ultimately, this is the only way to save lives and promote freedom.

JOHN YANG: Yohanan Plesner of the Israel Democracy Institute, thank you very much.

YOHANAN PLESNER: Thanks for having me.

JOHN YANG: For another perspective, we're joined by Dr. Mustafa Barghouti.

He's a leader of the Palestinian National Initiative, which advocates nonviolence and offers an alternative to both Hamas and Fatah, which is the major force in the Palestinian Authority on the West Bank.

Dr. Barghouti, as the head of a Palestinian organization that advocates nonviolence, what's your reaction or what was your response to what happened in Southern Israel?

MUSTAFA BARGHOUTI, Palestinian National Initiative: You are absolutely right when you say that I'm an advocate of nonviolence.

We were shocked about what happened.

I, as a person, always say that I am against any killing of any civilian, whether Palestinian or Israeli.

And we're sorry for all those people who were killed, Palestinians and Israelis.

But, unfortunately, everybody keeps avoiding the root cause of the problem.

And, unfortunately, what we see today is a very intensive campaign to dehumanize not Hamas only, but to dehumanize Palestinians completely.

And the war that Israel is conducting today is not at Hamas.

It is at the Palestinian people in Gaza.

The reality is that we are in this situation mainly because there has been an occupation, an Israeli occupation of Palestinians, of Palestinian land for more than 56 years, the longest occupation in modern history, an occupation that has transformed into a system, as Amnesty International described it, and Human Rights Watch, as well, and even the Israeli human rights organization B'Tselem, a system of apartheid, a much worse apartheid than what prevailed in South Africa.

This is the root cause why there are Palestinians who are turning to violence, because all hopes have been lost.

And Mr. Netanyahu, the prime minister of Israel, who came to power in 1996, killed every potential and every possibility for peace talks.

I am so surprised and really amazed that a person who's in charge of a democratic institute in Israel speaks about zero-sum game.

What does zero-sum game mean?

It means either us or them.

That is not a way to make peace.

Mr. Netanyahu said that all Palestinians in Gaza must evict their homes.

And then his military spokesperson said that all Palestinians in Gaza, the 2.2 million people, should evict to Egypt.

That is the meaning of zero-sum game.

It's about ethnic cleansing of all the population of Gaza.

This is something everybody should know.

Mr. Netanyahu raised a map of Israel annexing all of the West Bank, all of Gaza Strip, all of the Golan occupied territories.

That is what he's saying.

And he said he will change the situation for 50 years to come.

So what he meant is ethnic cleansing of Gaza and then annexing it.

That is not the way to peace.

That is what zero-sum game means.

JOHN YANG: You talk about the root cause, and there are -- there's a generation of Palestinians who reject your call for nonviolence, who feel that this is how they have to respond.

What do you say to them?

DR. MUSTAFA BARGHOUTI: I say to them and I try to prove to them that nonviolence is a much more effective way of achieving our freedom.

That's the best way of doing that.

But one should ask the question, why these young people go in that direction?

It's simply because they see no hope; 80 percent of young educated people in Gaza are under siege and are unemployed.

The poverty is unbelievable.

The GDP per capita in Israel is $56,000 per year, while it is less than $1,000 per year -- per capita per year in Gaza.

Yet, Gazans are obliged to buy products at Israeli market price.

These people don't see a hope, don't see a future.

That's why I'm calling for a peaceful resolution.

That's why I say, now, instead of talking about zero-sum game, we should move in the direction of immediate cease-fire, de-escalation, immediate release of all Israeli prisoners in Gaza, in exchange of releasing Palestinian prisoners in Israeli jails, who are 5,300, including some people who have been in jail for no less than 44 years.

And 1,260 of those prisoners don't even know why they are arrested.

They're not charged.

They're not taken to court.

Their lawyers don't know why they are arrested.

They're basically taken hostages.

So, release prisoners, exchange prisoners, have cease-fire, stop this madness that is going to happen, and let's open a road for peace and for a peace for resolution by ending occupation and allowing us and the Israelis to coexist and live in peace.

JOHN YANG: Dr. Mustafa Barghouti of the Palestinian National Initiative, thank you very much.

DR. MUSTAFA BARGHOUTI: Thank you, sir.

GEOFF BENNETT: And we will have continuing coverage of the Israel-Hamas war this entire week, including a one-hour prime-time special Friday.

"War in the Holy Land: A PBS News Special Report" starts at 8.30 p.m. Eastern.

Check your PBS station for local listings.