Nuclear negotiations between Iran and major powers look set to continue into the weekend.
Praising the "constructive" atmosphere at the Vienna talks, U.S. Secretary of State John Kerry said on July 10, "I think we have resolved some of the things that were outstanding and we've made some progress."
"Some progress has been made, but we are not there yet," Iranian Foreign Minister Mohammad Javad Zarif said earlier. "I doubt it will happen today. ... It seems that we are going to spend the weekend in Vienna."
A senior U.S. official said a preliminary April deal that set up the current negotiations has been extended until July 13, effectively setting a fourth target date for a final accord.
The six powers want limits on Iran's nuclear programs that could have a military use. Tehran denies it is pursuing atomic weapons.
Zarif also accused unspecified counterparts from the so-called P5+1 -- Britain, China, France, Germany, Russia, and the United States -- of changing their negotiating positions and using pressure tactics.
The previous day, an unidentified Iranian official told Interfax that Western countries had "toughened their stand" on conditions for easing sanctions against Tehran.
After blowing past a self-imposed deadline followed by two extensions, negotiators had given themselves until midnight on July 10 to complete a deal.
A deadline for getting an accelerated review of the deal in the U.S. Congress has passed.
On July 9, Kerry threatened to walk away unless Iran made "tough decisions" needed to clinch a deal.
The Iranians immediately fired back, accusing the United States and its European allies of engaging in "psychological warfare" and changing their positions at the last minute.
Kerry and other Western officials said Iran still hadn't made the difficult political decision to roll back its nuclear program.
European foreign policy chief Frederica Mogherini told CNN on July 9 that "important, historical decisions" remained to be made.
The negotiators are working to strike a deal under which Tehran would curb its nuclear program in exchange for sanctions relief.
Long-standing differences reportedly persist over inspections of Iranian nuclear facilities and Iran's nuclear research and development program.
Tehran is demanding that a United Nations embargo on conventional-weapons sales to Iran be lifted simultaneously with other Western economic sanctions if a deal is reached. Western countries say they always intended to keep the arms embargo because of Iran's support of militant organizations in the Middle East.
Russia has backed Tehran, with President Vladimir Putin calling for lifting all sanctions against Iran as soon as a deal is reached.
Speaking to reporters on July 10 in the city of Ufa, where a summit of the Shanghai Cooperation Organization is being held, Putin said that "compromise should be found."
"In my opinion, it will be found soon," he added.
Also on July 10, the EU said it had extended a freeze on sanctions targeting Iran until July 13 to “allow more time for the ongoing negotiations to reach a long-term solution to the Iranian nuclear issue.”
With reporting by Reuters, AP, Interfax, and AFP