The head of the United Nations' nuclear watchdog warned that rising global tensions, including the U.S. conflict with Iran, are increasing the risk of an expanding nuclear arms race.

Rafael Grossi, director general of the International Atomic Energy Agency, told The Telegraph that the current environment is unstable and could lead to wider proliferation if safeguards weaken.

"At some point, we are going to see a crack in the system. And then we'll have a domino effect," Grossi said. "It is a very, very fragile position."

Grossi described a growing concern that more countries could pursue nuclear weapons, pointing to renewed debates in nations across Europe and Asia.

"There are all these things which fill me with concern because I believe that a world with 20 nuclear weapon states or more would be extremely dangerous," he said.

The concern comes as the United States and Russia continue to hold about 90% of the world's nuclear warheads, while China's arsenal is expanding.

"We are seeing a very steady growth in nuclear arsenal," Grossi said of China's program. "So, do I see this with concern in a certain sense? Yes, because I think a world with less nuclear weapons is better than a world with more."

Grossi said the long-standing goal of nuclear disarmament is unlikely in the current climate.

"At this point in history, it is not something that we are going to be seeing," he said. "Of course it's an aspiration, it is there, we all want to move in that direction, but I am a realist."

On Iran, Grossi said any agreement with the United States would require verification by the IAEA to be credible.

"Any agreement is no agreement" without oversight, he said, calling unverified deals "an illusion" that cannot guarantee compliance.

"We know Iran very, very well, all the facilities. We are the only ones who could guarantee absolute impartiality in the work," Grossi added.

He also raised concerns about the practicality of military action to secure Iran's nuclear materials, noting risks tied to handling sensitive substances and accessing damaged facilities.

"Materials are a delicate thing to handle, to manipulate, to move around," Grossi said, adding that structural damage to sites could complicate any such effort.

Grossi said reinforcing nonproliferation commitments remains critical to maintaining global stability.

President Donald Trump on Wednesday said that a second round of talks between the U.S. and Iran could take place as soon as Friday as Pakistani intermediaries pointed to ongoing mediation efforts aimed at restarting negotiations to end the military conflict.

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