The sharp escalation of hostilities between Israel and Hezbollah has sparked fears of a full-scale conflict breaking out across the Middle East.

And whether that happens could come down to the so-called Axis of Resistance.

The Iran-backed state and non-state actors span Lebanon, Gaza, Iraq, Syria and Yemen.

The network has been building its capabilities for decades, dedicated to countering US and Israeli influence across the region.

The axis has been dealt several blows in recent weeks, with senior figures assassinated.

Iran's Supreme Leader Ali Khamenei was moved to a secure location after close ally Hezbollah leader Hassan Nasrallah was killed last week, a senior Iranian official said.

On Tuesday night, Iran unleashed a major attack on Israel, firing nearly 180 ballistic missiles at the country in response to the killing of Nasrallah and other senior Hamas, Hezbollah and Revolutionary Guard members.

Israel has vowed that "there will be consequences".

Questions have been raised about what capabilities remain across Iran's proxy groups.

And whether they will get involved in significant retaliation against Israel if the violence continues to spiral.

Here's a closer look at the key players in the current conflict.

Hamas and October 7

Almost a year ago, Hamas militants hit southern Israel with a deadly attack.

Israeli authorities said about 1,200 people were killed and 250 taken hostage when the group stormed across the border from Gaza on October 7.

Israel responded with a military offensive in Gaza that has killed more than 41,000 Palestinians and injured about 96,000, according to Gaza's health ministry.

The Islamist group first emerged in the late 80s after separating from the Palestinian branch of the Muslim Brotherhood.

The group, which is listed as a terrorist organisation by the governments of Australia, UK, US, and Canada, was elected in 2006 to govern the Gaza Strip after beating political rivals Fatah.

Experts have highlighted that Hamas' most influential ally in the region is Iran but the group also receives financial and political support from Türkiye and Qatar.

The group is a part of Iran's so-called 'Axis of Resistance' which also includes the Palestinian Islamic Jihad, the Houthis, Hezbollah and others.

In July, Hamas' political leader Ismail Haniyeh was killed while in his residence in Iran. 

The militant group blamed Israel for the killing but Israeli officials have not claimed responsibility.

Since the death of Haniyeh, Yahya Sinwar has taken on the Hamas leadership.

He has been described by Israel as one of the masterminds behind the October 7 attacks.

Hezbollah and the border

In the past week, Hezbollah has lost seven high-ranking commanders and officials, some who have been involved in the group since its establishment in the 1980s.

The group has been one of the major players in the Israel-Gaza war since it began almost 12 months ago.

Hezbollah was founded during Lebanon's 15-year civil war and came to the fore after Israel's invasion of the country back in 1982.

The Council of Foreign Relations says the Iran-backed militant group is driven by its violent opposition to Israel, and its resistance to Western influence in the Middle East.

The group operates in the country as both a political party and a militant group.

Hezbollah has suffered losses with recent attacks from the exploding pagers and walkie talkies to the killing of long-time Hezbollah leader Hassan Nasrallah.

According to the Lebanese Health Ministry, more than 1,600 people have been killed in Lebanon since October 8, when Hezbollah began firing missiles into Israel the day after Hamas attacked the country.

Most of the deaths in Lebanon followed Israel intensifying its military campaign in mid-September.

About a million people have been forced to flee their homes, according to Lebanese officials.

Israel has since said it had carried out "limited, localised, and targeted ground raids" against Hezbollah in southern Lebanon villages.

Israeli officials said these would not extend to Beirut amid fears of a ground invasion across the Lebanese border.

But overnight, the IDF posted on X that it was "now targeting Beirut".

Houthis and the Red Sea

The Houthis have been active since the beginning of the Israel-Gaza war.

The group has been attacking ships in the Red Sea since November last year, stating it was supporting "Palestinian resistance in Gaza".

The Houthis began targeting only Israeli ships but have since turned their attention to Israeli ports, and ships of any company that had other ships visit Israeli ports.

The Houthi movement is an Islamic fundamentalist movement that started in northern Yemen.  

They are among the main actors in the ongoing civil war in Yemen saying they opposed the foreign influence on the Yemeni government.  

The group's origins lie in Zaydism which is a small sect of Shiite Islam that is centred in northern Yemen. 

In September, the Houthis claimed responsibility for a missile attack against Israel, it was the first to reach central Israel since hostilities begun.

Yahya Sarea, Houthi's military spokesperson, claimed last month its missile had "succeeded in reaching its target" and that Israel should expect more strikes in future.

"As we approach the first anniversary of the [October] 7 operation, including responding to its aggression on the city of Hodeidah," he said.

There were no injuries reported after the Houthis' air strike on central Israel, according to the IDF, but a paramedic service said several people were slightly injured while "on their way to shelters".