But fresh from talks in Geneva with his Iranian counterpart, Kerry sounded a note of caution, telling US lawmakers he was not sure yet whether a comprehensive agreement was within reach.
World powers grouped under the so-called P5+1 "had made inroads" since reaching an interim deal with Iran in November 2013 on reining in its suspect nuclear program, Kerry said.
"We've gained unprecedented insight into it," Kerry told the Senate appropriations committee at the start of two days of intense congressional foreign policy budget hearings.
He stressed again that US policy was that Tehran would not acquire a nuclear weapon.
Taking aim at critics, such as Israel, that are opposed to the agreement, Kerry said they did not "know what the deal is."
"I caution people to wait and see what these negotiations produce. Since 2013, we have been testing whether or we can achieve that goal diplomatically -- I don't know yet," Kerry insisted.
The so-called P5+1 group of Britain, China, France, Russia, the US and Germany are trying to strike an accord that would prevent Tehran from developing a nuclear bomb.
The next round of talks is due to be held at the political director level on Monday in Switzerland, but US officials have said Kerry could join the negotiations again.
You’ve reached your limit of {{free_limit}} free articles this month.
Subscribe now for unlimited access.
Already subscribed? Log in
Subscribe to read the full story →
Smart Quarterly
₹900
3 Months
₹300/Month
Smart Essential
₹2,700
1 Year
₹225/Month
Super Saver
₹3,900
2 Years
₹162/Month
Renews automatically, cancel anytime
Here’s what’s included in our digital subscription plans
Exclusive premium stories online
Over 30 premium stories daily, handpicked by our editors


Complimentary Access to The New York Times
News, Games, Cooking, Audio, Wirecutter & The Athletic
Business Standard Epaper
Digital replica of our daily newspaper — with options to read, save, and share


Curated Newsletters
Insights on markets, finance, politics, tech, and more delivered to your inbox
Market Analysis & Investment Insights
In-depth market analysis & insights with access to The Smart Investor


Archives
Repository of articles and publications dating back to 1997
Ad-free Reading
Uninterrupted reading experience with no advertisements


Seamless Access Across All Devices
Access Business Standard across devices — mobile, tablet, or PC, via web or app
