President Joe Biden and Vice President Kamala Harris are deeply engaged in crisis talks to prevent a full-scale regional war between Israel and Iran following the assassination of Hamas leader Ismail Haniyeh by Israel, which has strained US-Israel relations. The White House and Secretary of State Antony Blinken are pushing for a decisive ceasefire deal to de-escalate tensions and facilitate the release of hostages in Gaza. Diplomatic efforts include intense communication with allies and regional players like Qatar and Egypt. Blinken has emphasized the urgency of concluding the ceasefire negotiations to avoid further conflict, calling on Hamas's new leader Yahya Sinwar to agree to the deal. US military posture has been strengthened to defend against potential Iranian reprisals, as the administration balances support for Israel with the need to prevent broader hostilities.