BANGKOK — President Barack Obama said Sunday that an incursion by Israel's forces into the Gaza Strip could deepen its own death toll, cautioning against an escalation even as he defended Israel's right to defend itself.

To Palestinians, Obama warned the latest crisis could crush peace hopes for years.

"Israel has every right to expect that it does not have missiles fired into its territory," Obama said at the start of a three-nation tour in Asia.

"If that can be accomplished without a ramping up of military activity in Gaza, that's preferable," he said. "It's not just preferable for the people of Gaza. It's also preferable for Israelis, because if Israeli troops are in Gaza, they're much more at risk of incurring fatalities or being wounded."

Obama's comments came as Israel's campaign against Hamas militants in Gaza blasted into its fifth day. Israel is at a crossroads of whether to launch a ground invasion or pursue Egyptian-led truce efforts. Obama sought to defend the U.S. ally's rights while pushing for a halt in the violence.

Israeli Prime Minister Benjamin Netanyahu declared Sunday that Israel was prepared to significantly expand its military operation in Gaza. Obama has been lobbying Netanyahu along with the leaders of Egypt and Turkey to try to halt the crisis — including stopping rocket strikes on Israel.

He said Israel was justly responding to "an ever escalating number of missiles that were landing not just in Israeli territory, but in areas that are populated. And there's no country on earth that would tolerate missiles raining down on its citizens from outside its borders."

Obama said Palestinians will have no chance to pursue their own state and a lasting peace with Israel as long as rockets are fired into Israel. He said he hoped for a clearer process over the next 48 hours — showing how much the Mideast conflict had intruded on his diplomatic mission to Asia.