i think the reasoning is clear but a short article is not conducive to chapter and verse. The US has not a clue how the Arab Spring will work out and who will be its friends. Egypt is likely lost.. Similarly Yemen. The US's budgetary problems mean it will be less adventuress in the Middle East, Pakistan and Afghanistan. Israel is clearly a strong US ally and because of the Arab Spring Israel is more important. than ever. Obama's hard line with Netanyahu should be viewd in a positive sense. Only with good friends can one be so nasty.
U.S. warns governments, bankers Iran sanctions still in place (Reuters)
from the article: Israel must tread carefully during the Arab Spring