When Israel scrambled two F-15 fighter jets last month to intercept an Egyptian airliner after faulty communication with the cockpit raised fears of a hijack, it took several tense minutes for the plane to be cleared to land.
Any last-resort shoot-down decision in such a situation could fall to Israel's defense minister if the prime minister were unavailable.
The defense post at the time was held by Moshe Yaalon, a former armed forces chief. The incident on April 23, after the plane-load of Christian pilgrims failed to identify itself on entering Israeli airspace, ended calmly.
Yaalon has since been replaced by Avigdor Lieberman, a far-right politician with meagre military experience and a reputation for having a "short fuse".
Lieberman, who was approved as defense minister by the government on Monday, is now battling to show he has the temperament and skill to hew to Prime Minister Benjamin Netanyahu's strategy of keeping security crises on a low flame.
Centrist opposition leader Isaac Herzog has warned of "war and funerals" following Lieberman's assumption of the second-most powerful cabinet post. Iranian newspaper Kahyan has likened Lieberman to the Islamic State insurgents fighting Tehran's regional allies in the Middle East.
Lieberman, who in the past ridiculed peace talks with the Palestinians and goaded Egypt and Turkey with critical comments, pledged "strong commitment" to building ties between Israel and its neighbours after signing the coalition deal with Netanyahu.
Two prominent former generals who have worked with Lieberman or advised him say the change of tone is significant, describing the veteran politician as attentive and circumspect in private.
"He is nowhere near as aggressive as his public image would suggest," said one of them. "I think that, as defense minister, he will continue in this vein. He knows what he doesn't know, and he knows how to listen to those that do know."
Many Israelis are not so sure. But some may be coming round.
A television poll aired on May 20, when it became public knowledge that Lieberman was being tapped for defense minister, found 27 percent of Israel's Jewish majority wanted him to have the job. More than half preferred that Yaalon stay on and 22 percent were undecided.
A week later, a television poll of the general public -- including the Arab minority -- found 44 percent thought he would be a good defense minister, 40 percent thought he would not, and 16 percent were undecided.
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Netanyahu says he will call the shots on core national security, but Israeli defense ministers have outflanked premiers before: Ariel Sharon pushed to deepen the 1982 Lebanon invasion, and historians say Moshe Dayan ordered an important offensive during the 1967 Middle East war despite instructions to hold off.
Amotz Asa-El, a fellow with the Shalom Hartman Institute, a liberal Israeli think tank, was skeptical about such comparisons.
He said Lieberman, whose Yisrael Beitenu party holds five of parliament's 120 seats, lacks those predecessors' political clout. Both Sharon and Dayan were also decorated veterans of the Israeli top brass, unlike one-time conscript corporal Lieberman.
"The dynamics around Lieberman are different," Asa-El said.
"Should he go rogue without Netanyahu's approval, for example by trying to turn a future war in Gaza into a more sweeping operation against the Hamas leadership, the senior military echelon are prone to team with Netanyahu against him."
Hours after the coalition deal was announced last week, an al Qaeda-aligned faction in the Gaza Strip launched a rocket into Israel. It caused no damage or casualties but the incident has been seen by some Israelis as throwing down the gauntlet before both Lieberman and Hamas, which has tried to maintain a ceasefire in the Palestinian enclave since the 2014 war there.
When Israel last appointed a "civilian" defence minister, Amir Peretz in 2006, Hamas abducted one of its soldiers to Gaza and Hezbollah guerrillas killed two others and spirited their bodies to Lebanon. Israel launched offensives on both fronts.
Those groups' fortunes have since waned as the Arab Spring shook up their support networks running through Egypt and Syria.
Egypt, which sees Israel as a partner for stabilizing the Sinai, has taken Lieberman's appointment in its stride, despite alarm in some circles in Cairo. Nor has Syria responded strongly. After years of civil war, Damascus is beholden to Russia, where the Soviet-born Lieberman is well regarded.
Hezbollah, too, is watching from the sidelines.
"Everyone is now analyzing Lieberman, the arrogant, lunatic minister of war in Netanyahu's radical government," Hassan Nasrallah, the leader of the Lebanese Shi'ite group, said in a speech last week.
"What does this mean? This also needs consideration. I do not want to rush to judgment."
REUTERS