The United States is the only country that can carry out a successful, preventative military strike against Iran's nuclear program, according to a study by the Center for Strategic and International Studies (CSIS), a well-regarded Washington-based think tank.
According to the study published in September, only the United States has the capacity to both deliver the explosive payloads needed in the initial strike and effectively carry out follow-up strikes based on continued near-real-time intelligence.
"The US would be the only country that has the air power, support capability, and mix of sea‐air forces in the Gulf to continue a sustained campaign over a period of time and restrike after an initial battle damage assessment [if] it is found that further strike sorties are required," the report said.
"Israel does not have the capability to carry out preventive strikes that could do more than delay Iran’s efforts for a year or two," the report said, adding, "a strike by Israel on Iran will give rise to regional instability and conflict as well as terrorism. The regional security consequences will be catastrophic."
The initial strike, CSIS said, would aim to take out Iran's heavily-fortified uranium enrichment and research facilities and ballistic missile sites.
Iran would not be impotent in the face of such a strike, the report said, targeting Israel and US financial and security interests in the Gulf States.
"Iran most probably will accuse Israel [of being] part of the strike and will try to retaliate, either by launching a Ballistic Missile on Israel carrying conventional or WMD (chemical, biological, radiological) and activating Hezbollah to launch cross border attacks against Israel," the report said.
In an apparent reference to the possibility that Israel will act against Iran without American consent, the report also stated that, "The US should alone determine what the timeline could be if Iran does pursue the path to develop nuclear weapons."
In recent weeks, the Prime Minister Binyamin Netanyahu has engaged in a public back-and-forth with US officials over establishing "red lines" for Iran on its nuclear developments, a step the US has refused to take. US President Barack Obama, however, said in March that "in the end, Israel's leaders will make determinations based on what they believe is best for the security of Israel, and that is entirely appropriate."
CSIS emphasized that the military option should only be used "if all peaceful options have been exhausted and Iran has left no other means to convince it to stop or change its course in pursuing Nuclear Weapons."
Because Iran's facilities are spread out and well-fortified, the report said, the ultimate effect of a US-led strike on Iran’s nuclear facilities remains uncertain.