DUBAI, United Arab Emirates — Israel launched a strike targeting Hamas’ leadership in Qatar on Tuesday as they considered a U.S. proposal for a ceasefire in the Gaza Strip. The strike on the territory of a U.S. ally marked a stunning escalation and risked upending talks aimed at winding down the war and freeing hostages.

Qatar, an energy-rich U.S. ally hosting thousands of American troops, has served as a key mediator between Israel and Hamas for several years, even before the war. It condemned what it referred to as a “flagrant violation of all international laws and norms” as smoke rose over its capital, Doha.

It was not immediately clear if anyone was hurt in the strike. Hamas has survived numerous assassinations of top leaders and is still intact in Gaza, despite having suffered majo

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