AMNA NAWAZ: Israel and the Lebanese paramilitary group Hezbollah have been trading fire across the tense border in a limited, but slowly escalating conflict.

Just today, Hezbollah fired missiles into Israel, injuring two civilians.

So far, the skirmishes have killed nine Israeli soldiers and four civilians, and more than 100 Lebanese, most of them Hezbollah fighters.

As special correspondent Simona Foltyn reports, Israeli officials have said they're prepared to invade Southern Lebanon, raising fears of a regional war.

SIMONA FOLTYN: Another Hezbollah fighter is laid to rest near Lebanon's Southern border, one of more than 100 killed since the group reopened this long-simmering front with Israel after the October 7 attacks.

Ali Moussa Barakat was killed in an Israeli strike.

In Hezbollah's words, he was martyred on the path to Jerusalem.

His death is celebrated, rather than mourned, in a struggle they consider holy.

There have been almost daily funerals like this, and they're very public.

That's in part because of Hezbollah's deeply rooted culture of martyrdom, but also to show that the group is doing its part in supporting its ally Hamas in the war with Israel.

With every death, defiance grows towards Israel and its closest ally, the United States.

"Death to America," they shout, as they vow to fight on.

Public expressions of grief are not welcome.

Monah Khalil, the mother of the slain fighter, does not shed a tear.

"We're Hezbollah until our last breath," she tells me, "and Israel knows the meaning of these words."

Just like for Palestinians, for Lebanese too, this conflict didn't start in October.

Before Ali, Monah lost two other sons, the youngest when Israel last invaded Lebanon in 2006, old wounds torn open again and again in a decades-long war that doesn't seem to end.

"They know that this is our land and we are within our rights," she says, before another mourner jumps in.

WOMAN (through translator): When Israel comes to take our land, we will not accept it.

We are obligated to give our blood to defend our homeland.

Our women and men are strong.

SIMONA FOLTYN: A warning directed at Israeli officials, who have called for foreign troops to create a buffer zone and push Hezbollah out.

The United States has designated Hezbollah a terror organization, but here it's called the resistance, a movement with widespread support among Lebanon's Shia that has become the de facto state.

"They should stop messing around and trying to bring a state here.

We have a state that is from us and within us, and our resistance is from us and within us."

Hezbollah draws much of its legitimacy from Israel's repeated violations of Lebanese sovereignty.

Israel first invaded in 1978 to fight Palestinian factions based here and again in 1982.

That's when Hezbollah was formed with Iranian support to fight the occupation, which lasted for 18 years.

Israeli troops withdrew in 2000, but the conflict flared again in 2006.

A U.N. peacekeeping force called UNIFIL has been here since the '70s and is supposed to keep a lid on fighting.

We travel to its headquarters in the border town of Naqoura.

The U.N. blue line which demarcates the border between Israel and Lebanon is just a mile-and-a-half that way, and we can actually see the border fence, as well as some charred areas that have been burned in recent Israeli strikes.

Hezbollah uses the thick vegetation around here to carry out guerrilla-style attacks, but Israeli shelling of Lebanon hasn't just killed fighters, but also at least 17 civilians, including three journalists, and injured eight Lebanese soldiers and two U.N. peacekeepers.

Andrea Tenenti is UNIFIL's spokesperson.

ANDREA TENENTI, Spokesperson, U.N. Interim Force in Lebanon: Any attack against our contingents or against civilians, of course, is against international laws, and the killing of civilians definitely against international law and may amount to war crimes.

SIMONA FOLTYN: The U.N.'s task is to monitor and investigate such violations, but this has become increasingly difficult as its troops come under fire.

ANDREA TENENTI: Definitely, the capability and the ability to patrol has been affected, because, during shelling, it's important also for our troops to be protected.

SIMONA FOLTYN: We accompany a Malaysian peacekeeping battalion patrol.

According to a 2006 U.N. resolution, Hezbollah is to withdraw around 15 miles north and hand over security to the Lebanese army.

But Hezbollah has become more powerful after the 2006 war and has refused to budge.

These hills are its stronghold and the launching pad for rocket attacks.

FAHMI MASWAN, U.N. Interim Force in Lebanon: We are conducting counter-rocket launching operation.

This operation is -- have the aim, which is we have to locate and also report the place or vicinity that have possibility for the rocket launching operation.

SIMONA FOLTYN: Patrols like this occur daily, but with little effect.

Since October, peacekeepers have found only three rocket launching platforms and they don't have the mandate to seize weapons or use force to stop attacks.

FAHMI MASWAN: Actually, we only report.

And the action are taken by the Lebanese armed forces.

SIMONA FOLTYN: So it's up to the Lebanese armed forces to prevent Hezbollah from launching attacks?

FAHMI MASWAN: Yes.

SIMONA FOLTYN: But many here say the Lebanese army lacks the capabilities and morale to challenge Hezbollah.

After Lebanon's economy and currency collapsed, Lebanese soldiers earn less than $100 per month.

They also lack political leadership, as the country reels from an unprecedented political crisis that has left it with no government.

Despite these challenges, some southern communities prefer the army over Hezbollah.

In the Christian town of Qlayaa, we meet Amin Saeed, one of the village chiefs.

AMIN SAEED, Qlayaa Village Chief (through translator): The best solution for our area is that the conflict stops, that the military operations stop and that the Lebanese army and the United Nations take over and that all parties agree to this.

SIMONA FOLTYN: Amin takes us to a viewpoint over the valley where Israel and Hezbollah have been trading cross-border fire.

More than half of the village's inhabitants have fled.

The farmland surrounding it has become off-limits as deadly shells rain down every day.

AMIN SAEED (through translator): These farms down there have been affected a lot.

The olive trees have been destroyed and there are walnut farms down there that have also been destroyed.

SIMONA FOLTYN: This is one of several areas where Israel has deployed white phosphorus, an incendiary weapon used to mark targets or create a smoke screen.

Rights groups say it may have been unlawful due to the proximity of populated areas.

AMIN SAEED (through translator): There was a lot of white phosphorus in these planes.

All the farmland has been destroyed.

SIMONA FOLTYN: Not long after we arrive, Israeli tanks begin firing across the border.

The valley behind us has seen intense shelling, but up here in the village of Marjayoun, it has remained relatively quiet, and that is because the Christian communities who live here have not allowed Hezbollah and Hamas to use their areas to launch attacks on Israel.

RIMON AOUN, Resident of Marjayoun, Lebanon (through translator): Any weapons other than those of the Lebanese army are forbidden, forbidden.

SIMONA FOLTYN: Rimon Aoun already lost his restaurant to Lebanon's economic crisis.

He doesn't want to also lose his land to yet another Israeli invasion.

He wants Lebanon and Hezbollah to stay out of this war.

RIMON AOUN (through translator): Why isn't Syria fighting for the Palestinians?

Why isn't Jordan fighting for them?

Why isn't Egypt fighting for them?

Why should we, Lebanon, bear this alone?

Should we turn Southern Lebanon into a second Gaza?

SIMONA FOLTYN: A question that's on everyone's mind as Israel widens its operations.

Every strike and every counterstrike could be the spark to ignite all-out war.

For the "PBS NewsHour," I'm Simona Foltyn in Southern Lebanon.