The United States on Sunday sharpened its criticism of Hamas and urged the militant Palestinian group to accept a cease-fire agreement that would halt nearly two weeks of fighting with Israel.
The White House said Secretary of State John Kerry would go soon to Egypt to press for a cease-fire to hostilities that have killed at least 425 Palestinians and 20 Israelis.
The Obama administration toned down its earlier rebuke of Israel for attacks on the Gaza Strip that have killed civilians, including children, although both President Barack Obama and Kerry expressed concern about the rising death toll.
"It's ugly. War is ugly," Kerry said. "And bad things are going to happen. But they (Hamas) need to recognize their own responsibility."
Both Obama and Kerry said Israel has a right to defend itself against frequent rocket attacks by Hamas from the Gaza Strip. Kerry accused Hamas of attempting to sedate and kidnap Israelis through a network of tunnels that militants have used to stage cross-border raids. He also urged Hamas to "step up and show a level of reasonableness, and they need to accept the offer of a cease-fire."
Then, Kerry said, "we will certainly discuss all of the issues relevant to the underlying crisis."
The nearly two-week conflict appeared to be escalating as U.N. chief Ban Ki-moon headed to the region to try to revive cease-fire efforts.
Obama, in a telephone call Sunday, told Israeli Prime Minister Benjamin Netanyahu that Kerry would be coming to the Mideast and condemned Hamas' attacks, according to a White House statement.
The U.N. relief agency in Gaza estimates that 70,000 Palestinians have fled their homes in the fighting and are seeking shelter in schools and other shelters the United Nations has set up. The relief agency's top director in Gaza, Robert Turner, told CNN's "State of the Union" that the U.N. has run out of mattresses for refugees and few hygiene and medical supplies are left, although fresh food and water remain available.
"People are scared," Turner said. "They don't feel safe at home, they don't feel safe with their families or neighbors. They feel relatively safe in our instillations. ... We frankly have been overwhelmed by the numbers."
He said more than 1,000 homes in Gaza have been destroyed or damaged beyond repair, and at least 13,000 lightly damaged.
U.S. officials made clear, however, that Hamas could bring relief to the Palestinian people if it agrees to a cease-fire proposed by Egypt — a view that Israeli Prime Minister Benjamin Netanyahu is pushing as well.
Hamas has rejected the Egyptian plan and instead is relying on governments in Qatar and Turkey for an alternative proposal. Qatar and Turkey have ties to the Muslim Brotherhood, which is also linked to Hamas but banned in Egypt.
Republican Sen. Lindsey Graham, a member of the Senate Armed Forces Committee, urged Israel to "stay as long as you need to stay, go wherever you need to go, do deal with a viper's nest called Hamas."
"If it's left up to Hamas, thousands of Israelis would be dead," Graham, R-S.C., told NBC's "Meet the Press."
Netanyahu agreed. In an interview with ABC's "This Week," he said Israel has tried to avoid killing Palestinian civilians through phone calls, text messages and leaflets dropped on their communities
But Hamas doesn't "give a whit about the Palestinians," Netanyahu said. "All they want is more and more civilian deaths."
The prime minister said his top goal is to restore a sustainable peace, but then will ask the international community to consider demilitarizing Gaza to rid Hamas of its rockets and shut down the tunnels leading into Israel. Netanyahu brushed off a question about giving concessions to Hamas as a step toward peace, including releasing Palestinian prisoners or loosening border crossings.
"Hamas doesn't care," Netanyahu said. "I think the last thing you want to do is reward them."
Kerry also said any cease-fire agreement must be without conditions or "any rewards for terrorist behavior." He did not mention the Qatari or Turkish efforts.
Kerry also blamed the latest wave of violence on what he called Israel's "legitimate" efforts to pursue and punish those who last month kidnapped and killed three Israeli teenagers whose bodies were found in the West Bank.
Their deaths were followed almost immediately by what authorities believe was a retribution attack on a Palestinian youth who was strangled, beaten and burned to death.
Tensions between Israel and Palestinian authorities have been simmering for years. They threatened to boil over this spring when Israel shelved nearly nine months of peace negotiations that were being personally shepherded by Kerry after Palestinian President Mahmoud Abbas agreed to create a unity government with Hamas.
"No country could sit by and not take steps to try to deal with people who are sending thousands of rockets your way," Kerry said.
Kerry spoke Sunday on all five major news network talks shows: NBC, CNN, ABC, CBS' "Face the Nation" and "Fox News Sunday."