Diplomats held yet another round of high-level talks over Iran's nuclear program on Wednesday in Geneva, including over five hours of negotiations between the top diplomats from Iran and the United States.
US Secretary of State John Kerry and Iranian Foreign Minister Mohammad Javad Zarif engaged in "substantive meetings," the State Department said, and took one break for a fifteen-minute walk along the Rhone River.
US officials on the ground told journalists to expect Kerry's departure at the end of the day. But instead, Kerry unexpectedly returned to his hotel for yet more conversation with his Iranian counterpart.
"Secretary Kerry is returning to Mandarin Hotel for another meeting with Foreign Minister Zarif," a senior State Department official said.
The talks, pressured by a deadline twice delayed, now center around a political agreement the parties hope to reach by the end of March.
The US, United Kingdom, France, Russia, China and Germany seek to end international concerns over the nature of Iran's nuclear program, which many suspect is military in nature.
In Washington, however, aides on Capitol Hill continue to work on the final touches of a bill that would "trigger" new sanctions on Iran should talks ultimately fail, or should Tehran violate terms of an interim deal that laid the groundwork for negotiations, formally known as the Joint Plan of Action.
Leadership in Congress, now under full Republican control, plans to introduce the bill by the president's State of the Union address.
But any bill from Congress regarding new, nuclear-related sanctions on Iran during international talks over its nuclear program will be vetoed by US President Barack Obama, the State Department said this week.
"Even with a trigger, if there's a bill that's signed into law, and it is US law, in our mind it is a violation of the Joint Plan of Action— which, as we've said, could encourage Iran to violate it," State Department deputy spokeswoman Marie Harf said on Tuesday.
"A sanctions bill, trigger or not, that is passed and signed into law by the president, which we've said we will not do... would be a violation of the JPOA," she continued. If a deal does not come to pass, Harf said, "we could put initial sanctions on Iran in 24 hours."
Harf added on Wednesday that a bill from Congress could "very well lead to a breakdown in these negotiations."
Obama briefed Prime Minister Benjamin Netanyahu by phone on Monday on "recent developments" in the negotiations. Diplomats at the table have given themselves until June to reach a final, comprehensive agreement.
Speaking ahead of the Geneva round, a source in the Prime Minister's Office said that Israel believes pressure on Iran should remain, and even be beefed up "until we see Iran dismantle the military elements" of its nuclear program.
The issue of the negotiations is one that comes up in every high-level discussion between Israeli and US officials, he said.
Israel has been critical of the US position in negotiations from the start, calling for an increase in pressure.
"Sanctions alone do not stop Iran's nuclear program. It was through negotiations that we got to the Joint Plan of Action," Harf added.