JERUSALEM - Israeli tanks and soldiers punched into the Hamas-led Gaza Strip on Saturday night as the nation's eight-day-old military campaign to destabilize the hard-line Islamist rulers moved into a more volatile phase.
Backed by Apache helicopters, Navy warships and artillery batteries, the Israeli ground forces moved into northern Gaza in an attempt to seize control of open fields and orchards along the border that have been regularly used by Palestinian militants to fire crude rockets into southern Israel.
Residents in northern Gaza hiding in their homes said Israeli soldiers were quickly confronted by Palestinian militants that had been lying in wait. Palestinians in the area reported intense firefights taking place but there was no immediate word on fighters killed on either side.
The ground offensive sets the stage for a deadly showdown that could significantly shake-up Middle East political dynamics by either cowing hard-line Hamas ideologues into moderating their views or propelling the Israeli-Palestinian conflict into a deadly new spiral of unpredictable violence.
Hamas leaders in Syria have called for Palestinians to rise up and start a third uprising targeting Israel. Soon after Israeli tanks rolled into the Gaza Strip on Saturday night, Hamas leaders vowed to fight to the "last breath."
"We promise you that Gaza will be your graveyard," Hamas spokesman Ismail Radwan said on the Islamist group's Al Aqsa television station.
Speaking to his nation as soldiers advanced into Gaza, Israeli Defense Minister Ehud Barak said the military campaign "will not be short or easy."
"We are not war hungry," said Barak. "But we shall not, I repeat - we shall not -- allow a situation in which our towns, villages and civilians are constantly targeted by Hamas."
In an effort to isolate the Gaza Strip, Barak imposed a naval blockade on Saturday night and ordered thousands more reservists to report for duty.
The United Nations Security Council called an emergency session on Saturday evening in New York and Secretary General Ban Ki-moon urged an immediate halt to Israel's invasion. Ban said he'd conveyed his "extreme concern and disappointment" to Israeli Prime Minister Ehud Olmert.
The U.S. State Department, in a statement released Saturday evening, echoed Israel's stated goals.
"We are working toward a cease-fire that would not allow a reestablishment of the status quo ante, where Hamas can continue to launch rockets out of Gaza and to condemn the people of Gaza to a life of misery," it read in part. "It is obvious that cease-fire should take place as soon as possible, but we need a cease-fire that is durable, sustainable, and not time-limited."
At the same time, "we have expressed our concerns to the Israeli government that any military action needs to be mindful of the potential consequences to civilians," the statement concluded.
Earlier in the day, before the invasion began, President George W. Bush, in his weekly radio address, backed Israel's use of force and said that Hamas must take the first step toward a cease-fire.
President-elect Barack Obama took no position. While Obama was "closely monitoring global events, including the situation in Gaza" according to his chief national security spokeswoman, Brooke Anderson, "There is one president at a time and we intend to respect that."
The Israeli ground operation is likely to quickly expand to Gaza's southern border with Egypt as Israel tries to choke off the supply of weapons ferried into Palestinian militants by a network of smuggler's tunnels.
More than 430 Palestinians and 4 Israelis have been killed since the Israeli military launched a devastating series of air strikes last Saturday on the Gaza Strip.
Israel methodically destroyed hundreds of Gaza Strip targets, including the Palestinian Authority's Gaza Strip parliament building, government offices, the largest university, police stations, and mosques the Israeli military claimed were used to store rockets or hide militants.
As part of the operation, the Israeli military has barred international reporters from entering Gaza, despite a court order directing them to let at least some journalists in to cover the unfolding conflict.
Television shots of the initial ground operations showed intense Israeli attacks. One strike along the Gaza coast created a massive fireball that lit up the night sky.
Israel's offensive came as tentative diplomatic efforts to bring the deadly conflict to a quick end failed to gather significant momentum over the weekend.
Several world leaders also have called for an immediate truce, though Israeli leaders have said that they won't agree to a new deal with Hamas that is not enforced by outside monitors, perhaps from the United Nations, the Arab League or forces loyal to pragmatic Palestinian Authority President Mahmoud Abbas.
Israeli leaders rebuffed early appeals for a 48-hour truce and Hamas vowed to keep firing rockets until Israel re-opened its borders to allow critical food, aid and supplies into Gaza.
The week-old confrontation has already devastated the Gaza Strip and pushed the 1.5 million residents into a new humanitarian crisis. Much of the Gaza Strip has been thrown into darkness. Aid groups are unable to deliver food and supplies because of the ongoing fighting. And hospitals have been overwhelmed trying to deal with 2,500 Palestinians injured in the fighting.
Before the ground operation began, an Israeli air strike hit a mosque in the northern Gaza Strip during early evening prayers, killing 11 worshippers and injuring at least 30 others, according to Palestinian medical officials.
Israeli leaders say the military operation is likely to be prolonged as they try to undermine Hamas and curb persistent Palestinian rocket fire from Gaza that has killed 10 Israelis in the last two years.
The perception that it's the aggressor plainly is hurting Israel. In Paris Saturday, more than 20,000 demonstrators marched, many chanting slogans like "Israel murderer!" In London, about 10,000 protestors chanted slogans such as "End the siege on Gaza" and "Stop the massacre!"
Both demonstrations — and others in other European capitals — preceded Israel's invasion.
Israel's moves are meant to oblige some tight political and diplomatic deadlines, said Shibley Telhami, a Middle East expert at the Brookings Institution and a professor at the University of Maryland.
One is a renewed UN effort to address Gaza, which will intensify next week. Another is upcoming elections in Israel. A third is the close of Mahmoud Abbas's recognized term as president of the Palestinian Authority. Obama's pending inauguration in Washington is a fourth.
Of the last, Telhami said, "I don't think there was any chance Obama would initiate negotiations with Hamas directly," he said.
But Israel, he continued, "would like to see a scenario were Hamas is somewhat less attractive for Obama to consider even indirectly dealing with them."
The problem is, Telhami added, "International public opinion is not on Israel's side on this. Public opinion is on Hamas' side."
Special correspondent Ahmed Abu Hamda contributed to this report from Gaza City, Gaza Strip. Margaret Talev contributed from Washington.
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