Updated

The fate of an Israeli army sergeant captured by Hamas and being held in Gaza has become murkier with the massive Israeli assault on the Palestinian territory.

Gilad Schalit, 22, was captured in June 2006 in a deadly cross-border raid by Hamas-allied militants on an outpost guarded by his tank unit.

Since then, he has become an Israeli national obsession. Musicians have composed songs in his honor, activists have staged a permanent demonstration outside the prime minister's house and world leaders have tried to mediate his release.

Although Israel has no direct political contact with the Islamic militant group, it has bargained fiercely for Schalit's freedom. Israel is willing to trade several hundred of its more than 8,000 Palestinian prisoners on Schalit, but negotiations have been bogged down by sharp disagreements over which prisoner would be freed.

After launching an intensive aerial bombardment against Hamas on Saturday, a senior Israeli military officer said Israel was not prepared to let Schalit's safety drive its strategy. He spoke Wednesday on condition of anonymity because he was not authorized to discuss policy issues.

The officer indicated Israel would demand Schalit's release as part of any deal to end the fighting in Gaza, but it was not likely to be a deal-breaker. His name barely has been mentioned as Israeli leaders list their minimum conditions for a new cease-fire.

Photographs of Schalit, who also holds French citizenship, show a fresh faced teenager — he was 19 when captured — and he is described as polite, a sports enthusiast and a good student.

Nothing has been heard from him in six months, his father Noam told The Associated Press Thursday. Noam Schalit declined to be interviewed further, while the Israeli attacks on Gaza were continuing.

As Israeli planes hammered Gaza's infrastructure and targeted its leaders and fighters, Hamas invoked Schalit's name to taunt its enemy.

"Of course, Gilad is now frightened, he's terrified," said an anchor on Hamas television said Thursday. "He must be asking himself, 'What's happening right now? What will happen to me?"'

A Hamas statement broadcast on radio challenged the Israelis to send ground troops into the Gaza. "We are waiting for you to enter Gaza to kill you or make you into Schalits."

Winning the return of Israeli captives — or even their corpses — is a cardinal tenet of the Israeli military, and lopsided prisoner exchanges have been common in the past. Soldiers are trained never to abandon comrades on the battlefield. The capture of two Israeli soldiers on the Lebanese border by Hezbollah, a Shiite Islamic militia allied to Hamas, was the trigger that set off the 2006 Israeli war in Lebanon.

Foreign Minister Tzipi Livni, a candidate for prime minister in next month's elections, angered many Israelis recently when she appeared to waver on Israel's commitment toward Schalit.

Although everyone wanted to see Schalit return safely, she said, "it is not a question of what we want or don't want. It is a question of what is and isn't possible. Not everything can be done."

Vice Premier Haim Ramon, indicating frustration at failing to free Schalit during a six-month truce with Hamas, said Thursday the Israeli assault on Gaza could only improve his chances. "The truce brought us no closer to returning Gilad Schalit. I am convinced that if there is a different reality at the end of this operation it will assist to bringing Gilad Schalit home."

The Associated Press contributed to this report.