Diplomats from Iran and world powers reconvened in Vienna on Tuesday to seek a deal reviving Tehran’s 2015 nuclear accord, with pressure mounting for results soon.

Negotiators from Iran and the remaining parties to the agreement — Britain, France, Germany, Russia and China — got back to work after a break of a little over a week to return to their capitals for consultations.

Officials say that the talks are reaching their final stage, though it’s unclear how long that might take. The negotiations have dragged on for months, punctuated by a long gap last year caused by the arrival of a hard-line new government in Iran. The current eighth round started just after Christmas.

The three Western European participants have been warning for a while that time is running out for a successful conclusion of the talks. They have argued that the accord will soon become an “empty shell” in light of Iran stepping up its nuclear program.

Iran insists that its program is peaceful.

On Friday, U.S. Secretary of State Antony Blinken signed several sanctions waivers related to Iran’s civilian nuclear activities. The move reverses the Trump administration’s decision to rescind them.

Iran’s foreign minister on Saturday welcomed the sanctions relief but called it insufficient.

In Beijing, Chinese Foreign Ministry spokesperson Zhao Lijian said Tuesday that the talks are “currently at a crucial juncture” and that all involved “should enhance the sense of urgency.”

“As the culprit in the Iranian nuclear crisis, the U.S. should thoroughly correct its wrong policy of maximum pressure on Iran and lift all illegal sanctions on Iran and third parties,” Zhao said. “On this basis, the Iranian side should resume full compliance.”

(AP)