The ex-GOP presidential candidate called Biden an “honorable and dedicated public servant.”
The State Department said the execution was an example of regime's "extreme brutality."
A U.S. citizen incarcerated by Iranian intelligence for the past several years was a longtime CIA operative tasked with gathering information on the Iranian regime and other American adversaries across the globe.
Roughly 10 civilians were killed immediately in the strike, after U.S. drones mistook a group traveling through al-Bayda province in central Yemen for an al Qaeda convoy.
The administration said it plans to continue slamming Iran on terrorism, human rights.
The unexpected departure of Syria's top rebel commander is stoking fears inside the Pentagon that militant Islamist groups have overtaken centrist opposition forces in the country.
The loss of Gen. Salim Idris, head of the secular U.S...
The Democratic senator said he may pursue a resolution on the issue instead.
The Republican acknowledged that Congress is unlikely to buck President Obama.
The announcement gives the administration crucial breathing room.
The State Department said it is still committed to "vigorously enforcing" sanctions.