Israel has degraded the fighting capabilities of its chief adversaries over the past year, including Lebanon's Hezbollah and the U.S.- and EU-designated Palestinian terrorist group Hamas.
But Yemen's Huthi rebels, who continue to fire missiles and drones at Israel, have proven a resilient foe despite Israeli attacks.
"Deterring the Huthis presents significant challenges," said Ahmed Nagi, a Yemen analyst for the Brussels-based International Crisis Group. "Israel lacks sufficient intelligence about the group and its operational capabilities."
Israel's success hinges on its ability to locate and destroy the Iranian-backed group's weapons facilities, a task that has "proven difficult so far," Nagi said.
Another challenge is geography. Yemen is located some 2,000 kilometers from Israel. The Huthis also control large swaths of the country, including their stronghold in the mountainous northwest and the Red Sea coastline.
Israeli emergency services work at the scene of a missile strike that, according to Israel's military, was launched from Yemen and landed in Jaffa, Israel, on December 21.
Even so, Israel has intensified its air strikes in recent weeks against the Huthis, despite the armed group posing a limited direct military threat to Israel. The escalating Israeli attacks have threatened to exacerbate the humanitarian crisis in Yemen.
Escalating Attacks
On December 26, Israel said it conducted air strikes on the main airport in Sanaa as well as power stations and "military infrastructure" at several Yemeni ports.
The head of the World Health Organization narrowly escaped death in the Israeli strikes on the airport that killed at least six people.
SEE ALSO: Israel Strikes Huthis At Yemen Airport, Prompting Iranian CondemnationIsrael's allies, including the United States and Britain, have also carried out strikes in Yemen.
The U.S. military said that it carried out air strikes against Huthi targets in Sanaa and along the Yemeni coast on December 30 and 31, including a "command and control facility and advanced conventional weapon production and storage facilities."
The Huthis have fired on U.S. naval forces and attacked international shipping in the Red Sea, disrupting a key global trade route.
SEE ALSO: Russia And Yemen's Huthis United In Their Animosity Toward The WestThe Israeli strikes came amid almost daily missile and drone attacks by the Huthis on Israel. Most of the attacks have been intercepted by Israel's air defenses and have caused little material damage. But they have triggered constant air raid sirens in many parts of Israel and disrupted everyday life.
The Huthis launched their attacks on Israel and international shipping in late 2023. It came soon after Israel began its devastating war in the Gaza Strip. The rebels have vowed to continue their attacks until a cease-fire is reached in the Palestinian enclave.
Protesters, mainly Huthi supporters, shout slogans as they rally to show support for Palestinians and Lebanon's Hezbollah in Sanaa, Yemen, on November 8.
Farzan Sabet, a senior research associate at the Geneva Graduate Institute, said Israel is largely operating against the Huthis in the dark. Israeli attacks, he said, have mainly targeted "civilian and strategic infrastructure rather than the military assets."
Civilians have borne the brunt of the violence in Yemen, where two-thirds of the population of some 35 million people need humanitarian assistance.
"We, the people, are paying for it, not the Huthis," said Mustapha Noman, a former Yemeni deputy foreign minister. "This helps them."
Iran's Trusted Allies
The Huthis are part of Iran's so-called axis of resistance, its loose network of proxies and militant groups against archfoe Israel.
Israel has severely weakened the axis over the past year. Israel's ground invasion and devastating air campaign in Lebanon decimated the military capabilities of Hezbollah, an armed group and political party in Lebanon.
Israel's ongoing war in the Gaza Strip has devastated the Palestinian territory and diminished the fighting power of Hamas.
SEE ALSO: Fall Of Assad Unravels Iran's Decades-Old 'Axis Of Resistance'Meanwhile, in early December, longtime Syrian President Bashar al-Assad, another member of the axis and a key ally of Iran, was ousted from power by Islamist rebels.
That has heightened the importance of the Huthis for Iran. The rebels are armed with highly capable ballistic missiles and are the least affected by the Israeli strikes.
"Without the Huthis, Israel would likely shift its full focus towards targeting and weakening Iran directly," said Nagi.