revived agreement to curb Iran’s nuclear program is “in sight,” the US said on Tuesday as international talks resumed in Vienna. Negotiators from Iran, Britain, China, France, Germany, and Russia returned to the luxury Palais Coburg hotel in the Austrian capital after a break last month for consultations with their governments. The US is involved in the talks indirectly. The aim is to restore the 2015 Joint Comprehensive Plan of Action, which collapsed in 2018 when the US pulled out. The JCPOA restricted Iran’s nuclear development in return for the lifting of economic sanctions. “A deal that addresses all sides’ core concerns is in sight, but if it is not reached in the coming weeks, Iran’s ongoing nuclear advances will make it impossible for us to return to the JCPOA,” the US State Department said. Iranian Foreign Ministry spokesman Saeed Khatibzadeh said that answers that “the US brings to Vienna will determine when we can reach an agreement. We have made significant progress in various areas.” Eric Brewer of the US nonproliferation watchdog Nuclear Threat Initiative said there remained “a combination of issues that require resolution,” including the scope of sanctions relief and what to do with nuclear equipment Iran had installed. “They are the final sticking points for a reason — they are contentious and require concessions that neither side has been willing to make so far,” he said. Russian negotiator Mikhail Ulyanov said the negotiating teams were “five minutes away from the finish line. A draft of the final document has been crafted. There are several points there that need more work, but that document is already on the table.” German Chancellor Olaf Scholz said the talks were at “the decisive moment.” However, a powerful group of 33 Republican US senators warned President Joe Biden that they would work to thwart any new deal unless Congress reviewed it and voted on its terms. Led by Sen. Ted Cruz, a long-time opponent of the 2015 nuclear deal, the senators told Biden they would use “the full range of options and leverage available.” The senators said any nuclear agreement with Iran was of “such gravity for US national security” that it would by definition be a treaty requiring the advice and consent of two-thirds of the Senate. Any deal that fell short of a Senate-ratified treaty would probably be “torn up in the early days of the next presidential administration,” they said.