Kerry Says U.S. Will 'Know Soon' if Iran Willing to Make Nuclear Deal

The United States will know soon if Iran is willing to seal a deal to assure the world it is not seeking to develop a nuclear bomb, Secretary of State John Kerry said Tuesday.

But fresh from talks in Geneva with his Iranian counterpart, Kerry sounded a note of caution, telling U.S. 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.

"And we expect to know soon whether or not Iran is willing to put together an acceptable, verifiable plan."

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 United States and Germany are trying to strike an accord that would prevent Tehran from developing a nuclear bomb.

In return, the West would ease punishing sanctions imposed on Tehran over its nuclear program, which Iran insists is purely civilian in nature.

The next round of talks is due to be held at the political director level on Monday in Switzerland, but U.S. officials have said Kerry could join the negotiations again.