Israel is bombing targets across many parts of Lebanon, striking senior militants in Beirut and apparently hiding bombs in pagers and walkie-talkies. Hezbollah is firing rockets and drones deep into northern Israel, setting buildings and cars alight.
 
But no one is calling it a war - not yet.
 
Israeli officials say they are not seeking war with Hezbollah and that it can be avoided if the militant group halts its attacks and backs away from the border. Hezbollah also says it doesn't want a war but is prepared for one - and that it will keep up the strikes on Israel that it began in the wake of ally Hamas' Oct. 7 attack until there is a cease-fire in Gaza.
 
Israel and Hezbollah have repeatedly traded fire since then - but the intensity rose to another level Monday, when Israeli airstrikes killed more than 270 people, according to Lebanese officials. That would make it the deadliest day in Lebanon since Israel and Hezbollah last went to war in 2006.
 
"If someone had told me or most analysts in summer 2023 that Hezbollah is striking Israeli bases in Israel, and Israel is striking southern Lebanon and parts of southern Beirut, I would have said, okay, that's an all-out war," said Andreas Krieg, a military analyst at King's College London.
 
The term hasn't yet been applied to the current conflict because "there haven't been any boots on the ground," but that might be "the wrong metric," he added.
 
Is there any agreed definition of war?
Merriam-Webster defines war as "a state of usually open and declared armed hostile conflict between states or nations." Scholars generally expand that definition to cover large-scale violence involving insurgents, militias and extremist groups.
 
But any attempt at greater precision is difficult since armed conflicts run the gamut from states clashing with tanks and fighter jets to lower-level fighting.
 
Sometimes states officially declare war, as Israel did after Hamas' attack last year.
 
It has not made a similar declaration with regard to Hezbollah, but it has linked its strikes against the group to the war in Gaza, saying last week that allowing tens of thousands of residents to safely return to the north is an objective in that conflict. Israel's defense minister, Yoav Gallant, also frequently talks about an ongoing war with Iran and its allies along "seven fronts," including Lebanon.
 
States often refrain from declaring war even when they are plainly engaged in one. Russia officially refers to its invasion of Ukraine as a "special military operation" and has banned public references to it as a war. The United States has not formally declared war since World War II, even as it took part in major conflicts in Korea, Vietnam, Iraq and Afghanistan.
 
Why does neither side want to call it a war?
Part of the reason neither Israel nor Hezbollah is using the word "war" is because they both hope to achieve their aims without setting off a more severe conflict - or being blamed for one.
 
"Though tensions are flaring, the situation in southern Lebanon is not that of a full-scale war as both Hezbollah and Israel hope to use limited means to pressure one another," said Lina Khatib, a Middle East expert at Chatham House.
 
With its rocket and drone attacks, Hezbollah hopes to pressure Israel to agree to a cease-fire with Hamas - a fellow Iran-backed militant group - and to avoid being seen as bowing to Israeli pressure.
 
Hezbollah has said it would cease the attacks if there were a truce in Gaza, but the prospects for such a deal appear remote.
 
Israeli Prime Minister Benjamin Netanyahu has vowed to do whatever is necessary to halt the attacks so that displaced Israelis can return to their homes.
 
"I think the Israelis are trying to either tell Hezbollah, you come to the negotiation table and we'll settle this through diplomacy, or we'll push you into a corner until you overreact," Krieg said. "And that will be the all-out war."
 
What might a full-scale war look like?
Until recently, experts generally agreed that any future war between Israel and Hezbollah would look like the war they fought in 2006 - but much, much worse.
 
For years, Israeli officials warned that in any future war with Hezbollah, the army would exact a punishing toll on Lebanon itself, destroying critical infrastructure and flattening Hezbollah strongholds. It came to be known as the Dahiyeh Doctrine, named for the crowded southern Beirut district where the militant group is headquartered, and that suffered heavy destruction in 2006.
 
Hezbollah, meanwhile, spent years expanding and improving its arsenal, and is believed to have some 150,000 rockets and missiles capable of hitting all parts of Israel.
 
The military build-up and threats created a situation of mutual deterrence that kept the border largely quiet from 2006 until October of last year. For most of the past year, the region has been braced for the worst, but both sides have showed restraint, and the talk of "all-out war" has been hypothetical.
 
That could change at any time.
 
"We've gone up a step, but we haven't yet made it to the penthouse floor," said Uzi Rabi, the director of the Moshe Dayan Center for Middle Eastern and African Studies at Tel Aviv University. "At the end, I don't see there's going to be any alternative to a ground operation."
 
Is it definitely a war if there's a ground invasion?
Any Israeli decision to send tanks and troops into southern Lebanon would mark a major escalation and lead many to categorize the conflict as a war. But the two don't necessarily always go hand in hand.
 
Israel officially declared war in Gaza nearly three weeks before it sent any ground troops in. Israeli ground forces have been operating in the occupied West Bank for decades, and in recent months have routinely launched airstrikes against militants, without anyone suggesting it's a war.
 
A limited Israeli ground incursion might still leave room for both sides to back down.
 
Of course, Lebanon would likely see a ground invasion as a blatant violation of its sovereignty and an act of war. But Beirut already accuses Israel of routinely violating its airspace and of occupying disputed territory along the border.
 
In fact, the two countries are already officially in a state of war, and have been since 1948.

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