Two weeks before crucial June elections, rival camps have refused to react to allegations that Hezbollah was behind the polarizing Hariri assassination in 2005.
Why does the line between coercion and torture seem so shadowy now?
Region sees it as a bulwark against Iran; US sees it as key to any peace deal.
When the leaders meet Monday, the US will push for progress toward a Palestinian state, while Israel will ask for a harder line on Iran.
Ahead of his Monday meeting with Obama, who supports a two-state solution, the Israeli prime minister wants to make Iran's nuclear ambitions the focus of regional diplomacy.
Western nations call it a terrorist organization. To Palestinians, it's a legitimate elected government, a resistance movement, or an oppressive usurper. So just what is Hamas?
It chaired a special meeting Monday of the Security Council that endorsed the idea of holding a Middle East peace conference in Moscow this year.
For a friendly foreign leader, a visit to the White House can be a visit to the woodshed.