U.S. Secretary of State John Kerry will travel to Geneva on Sunday for talks with Iranian Foreign Minister Mohammad Javad Zarif, a month before the deadline the parties agreed to reach a framework agreement over Tehran’s nuclear program. Kerry said on Saturday there are still "significant gaps" between the parties, and that President Barack Obama does not want to extend the talks again beyond their scheduled end – March 24 for the framework agreement; the end of June for a comprehensive agreement.

The Kerry-Zarif meeting takes place against the backdrop of growing tension between Israel and the United States over Prime Minister Benjamin Netanyahu’s planned speech before Congress on March 3. Netanyahu is expected tell Congress that the agreement is “bad and dangerous,” and to call for new sanctions against Iran.

As opposed to previous rounds, U.S. Energy Secretary Ernest Moniz is joining the talks in Geneva, as is Iran’s atomic energy chief Ali Akbar Saheli. Their participation in the talks could signal that decisions on key technical issues are near, such as the future of the heavy water reactor at Arak and Iran’s uranium enrichment program.

According to Western diplomats and senior Israeli officials, the United States and the five other world powers are waiting for answers to proposals Iran received in Munich two weeks ago. According to these sources, the proposals include the following principles:

1. Iran will be able to continue operating its 6,000–6,500 old-generation centrifuges to enrich uranium to a low level of 3.5–5 percent. It will not be able to operate new-generation centrifuges, and the existing centrifuges will be modified to reduce their enrichment capability.

2. Iran will have to remove most of its enriched uranium to Russia, where it will be turned into non-weapons-grade nuclear fuel. Iran will be able to keep 300 kilograms of low-enriched uranium, less than that required to produce a nuclear weapon.

3. The heavy water reactor at Arak will be modified to reduce the amount of plutonium it can produce.

4. The agreement will remain in place for 15 years, during which time Tehran will remain under the strict supervision of the International Atomic Energy Commission.

5. Sanctions will be lifted only gradually, in keeping with Iran’s fulfillment of its obligations.

The Western diplomats note that the proposals are meant to ensure that if Iran does move toward a nuclear weapon, it will need at least a year to enrich enough uranium to the 90-percent level required for one such weapon.

The main points of contention are over the centrifuges and sanctions. The Iranians have so far refused to remove any centrifuges, and they want all sanctions lifted immediately upon signing the agreement.