Tough issues remain unresolved, U.S. could walk away if decisions not made: Kerry

VIENNA, July 9 -- U.S. Secretary of State John Kerry said on Thursday some of the tough issues remain unresolved in the ongoing Iranian nuclear talks in Vienna, saying hard decisions must be taken very soon, warning the United Statescould walk away from the negotiation table if tough decisions are not made.

As the deadline of the ongoing nuclear talks approaching, difficult choices are needed to be made by sides involved in the talks for a comprehensive Iranian nuclear deal.

"Some of the tough issues remain unresolved," Kerry said, adding "We know that difficult decision don't become easier over time,those decisions must be taken very soon."

Kerry warned the United States could walk away from the negotiation room if "tough decisions" could not be made.

"We are not going to sit at the negotiation table forever," Kerry warned, saying if the tough decisions will not get made, the United States are "absolutely prepared" to get to an end of this process.

"You can't wait forever for the decision to be made," he said.

After 18 months of diplomatic efforts, a comprehensive deal is within reach despite some gaps remains in the text of the accord.

If no deal is agreed by 6 a.m. (0400 GMT), July 10, in Vienna, the U.S. congress would have 60 days rather than 30 days to review the agreement reached after the deadline, a longer process which sides worry that it might derail the accord.

However, the United States said the quality of the deal is more important than the racing with the clock, as the historical deal must be tested by at least a decade of period.

"We shouldn't get up and leave simply because the clock strikes middle night," Kerry said, stressing "the stake (of the talks) is very very high."

"We will not rush and we will not be rush," Kerry said, "all we are focused on is the quality of the agreement."

But the European Union(EU) seems to oppose further extension of the talks for the coming days.

"We are very close but if the important historical, political decisions are not made in the next hours, we won't (have) an agreement," EU foreign policy chief Federica Mogherini told CNN in an interview. "That moment of truth will come extremely soon, next hours I think."

A diplomatic source told Xinhua the accord "could be very hard to be reached" by the 6 a.m., July 10 deadline, but the clarification of Iran's past suspected nuclear activities (so called possible military dimensions or PMDs) is "likely to have been done," the source said.

It's still unclear how long would the nuclear talks last in the Palais Coburg hotel, as some gaps remain unresolved.

Responding to reporters, Iranian Foreign Minister Mohammad Javad Zarif said he would stay in Vienna as long as necessary.

"I will stay as long as necessary," Zarif told reporters from the balcony of the hotel.

Iran and the five UN Security Council permanent members plus Germanyhave been negotiating over the past 18 moths to reach a long-term deal over Tehran's controversial atomic plan.

During the period, Iran would suspend some sensitive nuclear activates, in return, Western nations would partially relief some sanction imposed on Tehran.