President Barack Obama is encouraging Israel to try to minimize civilian deaths in its ground push into Hamas-ruled Gaza.
Obama says he talked to Israeli Prime Minister Benjamin Netanyahu Friday about the Gaza operation and reaffirmed Israel's right to defend itself. He told reporters at the White House that no nation should accept rockets being fired into its borders.
Israel's movement follows a 10-day campaign of more than 2,000 airstrikes that had failed to halt relentless Hamas rocket fire on Israeli cities.
Israel stepped up its campaign after the Islamic militant group refused to accept an Egyptian truce offer.