Is Israel assassinating Iran nuclear scientists?

Haaretz  "The Telegraph also quoted Israeli officials as privately acknowledging the new U.S. administration is unlikely to sanction an air attack on Iran's nuclear installations and that President Barack Obama's offer to extend a hand of peace to Tehran puts any direct military action beyond reach for now.
"As such, the reported goal of Israel's covert campaign is to delay or interrupt the Iranian research program, without engaging in a direct confrontation that could lead to a wider war."

Iran's nuclear arms drive delayed. Iran: Mossad killed Iranian official "DEBKAfile's intelligence sources note that the current Israeli intelligence timeline for a nuclear-armed Iran was previously 2011. Yaalon did not go into the reasons for the delay, but our sources mention two:

1. His estimate represented the first official Israel evaluation of the scale of the destruction and havoc the Stuxnet malworm has wrought to Iran's most secret nuclear weaponization facilities. Up until now, only the nuclear reactor at Bushehr and the uranium enrichment plant at Natanz had been admitted to have been affected by the invasive virus.
2. The second factor seriously slowing progress is the tightening ring of sanctions which are keeping Iran from receiving the materials, replacement parts and new electronic and technical systems needed to bring its clandestine military nuclear program to fruition

What would America do without Israel to protect her?