Analysts believe that an expanded conflict could encourage foreign fighters to support Hezbollah and fight Israel.

People walk past posters of late Hamas leader Ahmad Yassin, late chief of Iran’s Quds Force Qassem Suleimani, Hezbollah chief Hassan Nasrallah and Houthi leader Mahdi al-Mashat at the Sabeen Square in Sanaa, Yemen [File: Khaled

The most closely watched border in the Middle East lies between Israel and Lebanon, the site of eight months of tit-for-tat attacks and a possible Israeli land assault on its northern neighbour.

Israeli officials have repeatedly threatened to intensify attacks, saying they’re necessary to defeat Hezbollah and return 90,000 Israelis evacuated from their homes in the north since fighting started in early October.

But as Israel’s rhetoric escalates, Lebanon’s Hezbollah has responded with defiance, warning that such a conflict would not only impact Israel more than it thinks, but that it would be felt regionally.

Backing Hezbollah up regionally, analysts say, is the so-called “axis of resistance”, a regional network of armed groups, backed by Iran, who have started to make their presence known since Israel launched its brutal war on Gaza.

On October 7, a Hamas-led attack on Israel killed 1,139 people and took approximately 240 captive into Gaza. Israel immediately launched an assault that has decimated Gaza. Hezbollah began engaging Israel over the border the next day, aiming to divide its focus on Gaza.

Support, but how?

“The axis will participate in confronting any military action by Israel against Lebanon,” Kassem Kassir, an analyst close to Hezbollah, told Al Jazeera.

However, when a recent media report suggested that non-Lebanese armed fighters were ready to volunteer to head for Lebanon to fight with Hezbollah, a brief flurry of questions arose. How would the “axis” participate? Would it be the groups or individuals heading randomly into Lebanon?

“We told them: ‘Thank you, but we are overwhelmed by the numbers we have,” Nasrallah said in the speech, adding that Hezbollah already had more than 100,000 fighters.

If Israel shifts its focus from Gaza to Lebanon, the regional calculus could change as the scope widens.

“If the United States of America continues to support this usurping entity and attacks Lebanon and attacks Hezbollah, America should know that it has made all its interests in the region and Iraq a target and a danger,” Qais al-Khazali, the leader of Asa’ib Ahl al Haq, an Iraqi member of the axis of resistance, wrote on social media on Monday.

The term “resistance” in “axis of resistance” refers to the largely Shia, pro-Iranian regional network’s opposition to the United States and Israel, which means the members could choose any number of regional targets, in addition to attacking Israel from the locations they’re based in, alone or in concert.

Growing coordination

As Hezbollah cemented itself as a regional power and a pivot in the axis of resistance, its influence extended into Syria, Iraq and Yemen, where it coordinates logistics, operations and training with like-minded groups.

“Many of the groups, especially those that are transnationally inclined in the axis, will be asked by Hezbollah leaders in different countries to help and support them,” Renad Mansour, Iraq Initiative project director at Chatham House, said.

Those groups could include parts of the Popular Mobilisation Forces (PMF) in Iraq, the Houthis in Yemen, or foreign and local fighters in Syria that have backed President Bashar al-Assad in his war against the country’s opposition.

“Perhaps more than any other group in the axis of resistance, the Houthis view their relationship with Hezbollah as foundational,” Nick Brumfield, an independent Yemen analyst, said.

“Hezbollah has been the main contractor in providing axis assistance to the Houthis for years, and as a fellow Shia Arab movement, there is arguably a greater affinity between the two than between the Houthis and Iran.”

Until now, the Houthis have mostly focused on attacking vessels in the Red Sea they deem to be connected to Israel. But should cross-border attacks by Israel and Hezbollah intensify, maritime traffic in the Mediterranean may also face disruption.

On Sunday, the Houthis and the Islamic Resistance in Iraq claimed a joint raid on four vessels in Israel’s Haifa port.

While this attack may have established a new dynamic, the two groups have coordinated for years. A Houthi representative has long been present in Baghdad, while some PMF groups have had longer, historic relationships with the Houthis, according to Mansour.

These groups will likely want to mobilise should Israel and Hezbollah’s engagement escalate.

“One prospect will be intensifying the joint attacks carried out by the IRI and Ansarullah [the Houthis] and perhaps expanding that small partnership to include more armed actors,” Tamer Badawi, an Iraq analyst focusing on politics and security, told Al Jazeera.

“Those attacks are likely to be incremental toward Israel corresponding to the rhythm of [Israel’s] attacks on southern Lebanon or other parts of the country.”

“If the Houthis are making it more challenging and riskier for ships to navigate to Israel through the Red Sea, targeting the ones bound to Israel via the Med[iterranean] … would apply extra pressure on Israel,” Badawi said.

Much like in the Red Sea, attacks on ships do not need to directly strike sea traffic to affect Israel, shipping companies and the global economy.

“As insurance costs increase, importing costs increase, thus adding to the economic pressure [on Israel],” Badawi added.

Is a wider war coming?

How an expanded war between Israel and Hezbollah would go is still not known, despite the two having intensified their rhetoric in recent weeks.

Israeli officials declared last week that the country is ready for an “all-out war” with Lebanon.

Nasrallah countered with the prospect of regional allies coming to Hezbollah’s aid and a threat to Cyprus should it cooperate with Israel, despite Cypriot denials.

“This is the strategic messaging response and it is a parallel conflict to the physical combat on the ground,” said Seth Krummrich, a former special forces officer who is now at Global Guardian risk management firm.

This messaging is occurring on the back of US envoy Amos Hochstein’s visits to the region and ongoing negotiations over a potential ceasefire in Gaza. Krummrich said each side is trying to tell its domestic audiences that they will not be bullied, while also showing their opponents that “they don’t hold all the cards”.

Over the last eight months, analysts have maintained that there is a possibility of a limited ground invasion or – the more likely scenario – an expanded aerial war in which Israel targets areas that are Hezbollah strongholds, as well as Lebanese infrastructure.

Al Jazeera’s Sanad Agency has not found a significant Israeli troop build-up on the border with Lebanon. But cross-border attacks intensified in recent weeks, with Israel killing a top Hezbollah commander and Hezbollah responding with its largest barrage of rockets and missiles since October.

Meanwhile, Israel has also reportedly continued to use white phosphorus in south Lebanon.

That intensification could continue, with a “strategic escalation this week going into next week as [Israel’s Prime Minister Benjamin] Netanyahu visits the US”, Krummrich said.

In an expanded aerial war, the “axis of resistance” might continue to launch attacks on Israeli bases and targets outside the country.

In a recent video published by Hezbollah, the group showed what appears to be a series of targets inside Israel and spots in the Mediterranean Sea that it would seemingly target.

A land invasion, however, could lead to foreign fighters flowing into Lebanese territory, should the group feel it to be necessary.

Nasrallah said the group has more than 100,000 fighters and is already “overwhelmed” with the number of personnel at its disposal. But Israeli boots on Lebanese territory could change the status quo.

“Resistance axis groups have primarily wanted to use Israel’s assault on [the] Palestinians as a way to put themselves out as champions on the right side, and to challenge other Arab countries who have normalised relations [with Israel] but not necessarily to go and fight a war in southern Lebanon or in Palestine,” Mansour said. “I think this changes if you have an Israeli invasion of southern Lebanon and Hezbollah.”

“Until now, the appetite has been more domestic… but in the course of an Israeli invasion or escalation these groups will be asked to support and that will change the equation.”