Is Congress forcing the US to push for UN sanctions?

The US nuclear policy community seems to be telling the story these days that the US Congress has threatened to pass a unilateral sanctions law against Iran that would have much more than enough support to override any veto by Obama. To prevent this law from passing, according to this story, Obama is forced to push sanctions through, even in the wake of the diplomatic breakthrough reached by Turkey, Brazil and Iran.

On the face of it, its a plausible explanation. But more deeply, even if it is an explanation, it paints a worse picture of the situation, not a better one. The US Congress is the branch of the US government most susceptible to Israeli pressure. To the degree that US foreign policy cannot be conducted independent of the US Congress, Israel has a veto on US foreign policy initiatives.

If that is the case, if apologists for the Obama administration's spastic acceleration of the sanctions drive when news was released of the deal struck by Turkey and Brazil are correct, then the United States is committed to support Israel at whatever cost is necessary unless or until it breaks under the strain.

Russia so far has traded support for sanctions for postponing missile defense in Eastern Europe. China seems to have averted US pressure over its currency policies. (I find the US denial of this unconvincing.) The United States may continue to sacrifice its own interests for the principle that about 5 million Jewish people in Palestine should have a majority state.

Overall Russia, China and others getting concessions may be a good thing. Russia and China will make their own decisions about what they how they can use their security council vetos to their advantage with respect to the United States on this issue. In the calculation will be that this will damage their relations with Iran but the United States has resources adequate to compensate these countries for that.

Whether forced by Congress or not, a sanctions bill will increase hostility with Iran and most directly reduce cooperation and thereby make the US positions more difficult in Iraq and especially Afghanistan. Can the US Congress order the President of the United States to sacrifice the lives of US troops to the principle that none of Israel's neighbors can have the type of nuclear program Brazil, Japan, Germany and Canada have? Obama's supporters say the answer is yes. That answer does not reflect well on either the US or its ability to negotiate in good faith with Iran or anyone else on any issue related to Israel.