The House has passed legislation that gives President Obama authorization to impose additional sanctions against Iran.
Iran has failed to meet UN requirements that it take verifiable steps to ensure that its not using its nuclear program to create weapons. Key among them - a promise made by Iran - but later reneged - that it would send its enriched uranium overseas.
There have been indications recently that may have enough enriched uranium now to build a bomb. Obama had promised during his Nobel Peace Prize acceptance speech that he would increase efforts to stop the proliferation of nuclear arms in the world. The administration also warned Iran that continued non-compliance would lead to increased sanctions.