Alan Gomez and Michele Chabin

USA TODAY

The U.S. Congress approved a $225 million package to replenish Israel's missile defenses Friday, after the Jewish state's cease-fire with Hamas unraveled and Israeli forces pushed deep into Gaza in search of a missing army officer.

The money is directed toward restocking Israel's Iron Dome, which has been credited with shooting down dozens of incoming rockets fired by Palestinian militants over 3½ weeks of war. The bill now goes to President Obama, who is expected to sign the bill swiftly into law.

The Israel Defense Forces suspects 2nd Lt. Hadar Goldin, 23, was kidnapped and dragged into a Hamas tunnel during a battle that killed two Israeli soldiers. The abduction risks a major escalation in the nearly 4-week-old conflict, considering the extraordinary lengths Israel has gone to get back captured soldiers.

At a White House news conference earlier Friday, Obama reiterated his support for Israel's right to self-defense while urging greater protection for Palestinian civilians. He called for the immediate release of the soldier believed to be captured by Hamas and said it would be hard to put together another cease-fire after a 72-hour humanitarian truce collapsed almost immediately after going into effect Friday morning.

He also cited Iron Dome as a concrete way the U.S. is helping "make sure that Israel is able to protect its citizens."

At least 140 Palestinians and two Israeli soldiers were killed Friday. Fighting near the border with Egypt continued into the night, with residents reporting airstrikes and heavy tank and artillery shelling. The Israeli military said it was searching for the missing soldier and sent automated calls or text messages to residents to stay indoors.

Three years ago, Israel released more than 1,000 Palestinian prisoners in exchange for a captured soldier.

In 2006, the capture of 19-year-old soldier Gilad Shalit during a raid near the Gaza border started an intense, five-year campaign to win his freedom that gripped the nation.

During his five years in captivity, Israelis commemorated each of his birthdays and the anniversaries of his capture with mass demonstrations. His image was plastered on posters and TV screens across the country. Israel called in negotiators from Egypt and even former U.S. president Jimmy Carter for help.

In 2009, the Israeli government released 20 Palestinian women prisoners just for video proof that Shalit was alive and well. His release in 2011 was finally secured after Israel released 1,027 prisoners.

Within hours of his capture Friday, Goldin's family pleaded for the same kind of efforts to win back their son.

"We urge our soldiers to leave no stone unturned in your search for our son," Simcha Goldin, Hadar's father, said outside his home in Kfar Saba, a suburb of Tel Aviv.

A longtime friend of Hadar Goldin's told the Associated Press he is engaged to get married and that he studied at a religious Jewish seminary in the West Bank settlement of Eli. Goldin has a twin brother who is also in the military on the Gaza front-lines, said the friend, who spoke on condition of anonymity because he did not have the family's permission to discuss Goldin's personal details with the media.

Goldin's apparent abduction is kindling concerns about how many prisoners Israel has handed over to secure the release of so few hostages, especially after many in the USAquestioned whether the government gave up too much when it released five Taliban prisoners held at Guantanamo Bay to win the release of captured Army Sgt. Bowe Bergdahl.

Jon Alterman, director of the Middle East Program at the Washington-based Center for Strategic and International Studies, said that, unlike Americans, most Israelis are required to serve in the military.

"There's not a separate class of Israelis who serve in the army. They see the army as the pre-eminent national institution because so many have served in it," he said. "Therefore, when a soldier is kidnapped, it is not an abstract idea. It's a very personal event."

Alterman cautioned that the practice of hostage-for-prisoner swaps has led to Israel stockpiling prisoners in anticipation of the next soldier being captured, creating a constant incentive for Hamas or other groups to capture more hostages.

"That's the dangerous dynamic, because it leads both sides into a place they don't want to be," he said. "It's undesirable on both sides, but it seems unavoidable on both sides."

The Iron Dome defense system has emerged as a game-changer in the current round of violence with Israeli officials citing a success rate as high as 90%. It uses radar, advanced tracking technology and anti-missile batteries to follow the trajectory of an incoming rocket or mortar and determine if it is headed for a major population center.

Created by Israel's Rafael Advanced Defense Systems, Iron Dome has enjoyed strong U.S. technological and financial support. Throughout its history, the U.S. has provided more than $700 million to help Israel cover costs for batteries, interceptors, production costs and maintenance, the Congressional Research Service said. The total now appears set to climb above $1 billion.

Contributing: Associated Press