* Troops train while top brass rattle sabres
* Israel fears spillover from Syrian turmoil
* Hezbollah may hit back for any war on Iran
By Dan Williams
REVIVIM, Israel, March 7 (Reuters) - Wary of a spillover from the conflict in Syria, Israel is preparing to take on the Hezbollah militia that it suspects is getting advanced weapons from a distracted Damascus.
The Jewish state believes the Lebanese Shi'ite guerrillas also stand ready to retaliate if it carries out long-threatened strikes on the nuclear sites of Iran, another Hezbollah patron.
Hezbollah fought Israel's far more advanced forces to a standstill when they last came to blows, in 2006, and rained more than 4,000 rockets on northern Israel. A U.N.-monitored ceasefire has largely held since.
But a senior Israeli officer from the Lebanese front said on Thursday that tensions in Syria "had the potential to spill over and trigger a confrontation" with Hezbollah.
"We want to preserve the quiet, and we want the other side to know that if they take a step that necessitates we exact a price, they will pay dearly," the officer, who declined to be named, told foreign reporters while overseeing a simulated, regiment-strength battle with Hezbollah in a desert army base.
Israel is on the verge of being drawn in to the two-year Syrian insurgency.
About 20 U.N. peacekeepers were detained in Syria near the Israeli-occupied Golan Heights on Wednesday by fighters linked to the mainly Sunni Muslim armed opposition groups fighting to topple President Bashar al-Assad, who follows the Alawite faith derived from Shi'ite Islam.
Israeli U.N. Ambassador Ron Prosor has also written to the 15-member U.N. Security Council to complain about shells from Syria landing in Israel, warning it "cannot be expected to stand idle as the lives of its citizens are being put at risk".
Iran's nuclear ambitions could also prove to be a flashpoint. Widely believed to have the Middle East's only nuclear arsenal, Israel has threatened force to deny its arch-foe the means of making a bomb should international diplomatic alternatives fail. Tehran, which denies seeking nuclear weapons, has threatened wide-ranging reprisals if attacked.
The desert exercise reflected the enhanced training of Israeli forces which, combined with the sabre-rattling of top brass, suggested an attempt to deter Hezbollah by warning that the next conflict could bring greater suffering for Lebanon.
"The way they behave will have repercussions on the population and infrastructure of southern Lebanon," the senior Israeli officer said, referring to Hezbollah's heartland where Israel suspects it has sown rocket launchers and gun-nests in Shiite villages.
In 2006, Israel killed 1,200 people in Lebanon, most of them civilians, according to the United Nations. Hezbollah killed 160 Israelis, most of them soldiers within Lebanese territory.
Though sworn to Israel's destruction, Hezbollah casts itself primarily as Lebanon's defender. It says its arsenal has been unaffected by the Syrian turmoil and that it is now capable of paralysing Israel with long-range rocket strikes, if war erupts.
Asked if such a war would be more asymmetrical than in 2006, the senior Israeli officer said: "Yes. I don't in any way expect the casualty ratio to be similar. I want things to be as bad as possible for the other side and as good as possible for us."
He said Israel would try to give Lebanese civilians enough opportunity to evacuate - "such that I hope non-combatants will be significantly fewer than 40 percent (of casualties)".
Demonstrating Israeli plans to overrun Hezbollah-held ground quickly and suppress cross-border rocket salvoes, the troops who drilled on Thursday dashed across hillocks towards 10 mock guerrilla emplacements that had been raked with tank and machine-gun fire.
The exercise assumed around 100 Hezbollah fighters would face off against the 200 soldiers and Israel's heavier ordnance - an indication of the army's tactics of superior deployment.
The Israelis were all reservists, ages ranging from the mid-20s to early 40s, and trained to back up the standing army should it get bogged down on the Lebanese or other fronts.
One captain, who in civilian life is writing a doctoral dissertation on Balkan and Caucasus guerrillas, voiced a regard for Hezbollah that was more than merely academic.
"They have grassroots support and they fight on home turf," said the captain, who gave only his first name, Yiftach. Though he said he and his comrades were better prepared for war than in 2006, "Hezbollah worries me, to tell the truth".
The regiment's commander, Lieutenant-Colonel Yogev Bar-Sheshet, acknowledged Hezbollah had improved its capabilities.
But he added: "We train all the time for various possibilities, for scenarios. If we need to fight, be it tomorrow morning, or in another week or year, we will be the best that we can be and we will win."
Speaking to high school students last week, Israel's armed forces chief, Lieutenant-General Benny Gantz, appeared to acknowledge the dangers Lebanese civilians could face.
"Would it be better to be a citizen of the State of Israel in the next war or a Lebanese citizen in the next war? Better to be Israeli citizens," he said. (Editing by Jeffrey Heller and Alison Williams)