Palais Coburg in Vienna where negotiations to revive the 2015 Iran nuclear deal are being held. Photo: Reuters/Leonhard Foeger

The chances of reviving the 2015 Iran nuclear deal are shaky at best and Washington is ready to tighten sanctions on Tehran and respond to “any Iranian escalation” with Israel and other allies if it cannot be saved, the United States’ Iran envoy said on Wednesday.

“We do not have a deal with Iran and prospects for reaching one are, at best, tenuous,” US Special Envoy for Iran Rob Malley said in prepared congressional testimony, saying that if the accord could not be resurrected, the United States was “ready to continue to enforce and further tighten our sanctions … and to respond strongly to any Iranian escalation, working in concert with Israel and our regional partners.”

Under the agreement, called the Joint Comprehensive Plan of Action (JCPOA) and struck by Iran and six major powers in 2015, Tehran limited its nuclear program to make it harder for it to get a bomb in exchange for relief from economic sanctions.

Then-US President Donald Trump withdrew from the accord in 2018 and reimposed harsh US sanctions, and Iran began violating the nuclear limits a year later. President Joe Biden has sought to revive the accord, but indirect talks in Vienna unraveled in March, and it is not clear whether they might resume.

In remarks prepared for delivery before the Senate Foreign Relations Committee, Malley criticized Trump’s decision, saying this had not produced “longer and stronger” limits on Iran’s program but rather left them “shorter and weaker.”