President Barack Obama and Israeli Prime Minister Benjamin Netanyahu will meet for the first time since a rash of civilian casualties during Israel's summer war with Hamas in the Gaza Strip heightened tensions between the two leaders who have long had a prickly relationship.

Much of Wednesday's Oval Office discussion is expected to focus on another delicate issue: U.S.-led nuclear talks with Iran. With a deadline for reaching a final agreement less than two months away, all sides say significant gaps remain.

Netanyahu has long cautioned the U.S. and the international community that Iran is barreling toward a nuclear bomb and using the diplomatic openings as a stalling tactic. The Islamic republic contends its nuclear program is for peaceful purposes.

The Israeli leader arrives in Washington following meetings at the United Nations, where he delivered a blistering speech accusing Hamas of committing war crimes by using Palestinian civilians as human shields during the 50-day Gaza war that ended Aug. 26. His speech was a response to Palestinian President Mahmoud Abbas' assertion that Israel had carried out a "war of genocide" during the Gaza fighting.

Israel launched thousands of airstrikes against what it said were Hamas-linked targets in the dense Gaza Strip, resulting in more than 2,100 Palestinian deaths, the vast majority civilians, according to the United Nations. More than 70 Israelis were also killed

The civilian death toll in Gaza deeply frustrated U.S. officials and resulted in more biting public condemnations of Israel's actions than is typical from the Obama administration.

In his speech to the U.N. General Assembly, Netanyahu sought to equate Hamas with the violent Islamic State militants the U.S. is seeking to degrade in Iraq and Syria.

"ISIS and Hamas are branches of the same poisonous tree," he said, referring to the Islamic State group by one of its acronyms. He added: "When it comes to its ultimate goals, Hamas is ISIS, and ISIS is Hamas."

Obama and Netanyahu last met in March while the Israelis and Palestinians were still engaged in a U.S.-mediated peace process. The discussions collapsed without a peace accord.

Both Netanyahu and Abbas appear to have abandoned any hope of reviving peace talks, though each is pressing separate diplomatic initiatives. Netanyahu has called for bringing an alliance of moderate Arab states into the peace process, while Abbas has said he'll appeal to the U.N. Security Council to back Palestinian independence.