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Igor Ivanov joined four US and European statesmen in signing a plea for the fighting to stop before it escalates into a nuclear conflict.
The intervention by Mr Ivanov, who was the face of Russian diplomacy under both Mr Putin and his predecessor Boris Yeltsin, makes him one of the most prominent Russian figures to have called on the Kremlin to make peace.
He served as foreign minister from 1998 until 2004, when he was replaced by incumbent Sergey Lavrov, and remained in Mr Putin’s administration as secretary of Russia’s top security council until 2007.
Now the head of a Russian foreign policy think tank, he put his name to a statement published by the European Leadership Network which said Russia and the West had a common interest in preventing a nuclear war.
“The ongoing conflict in Ukraine elevates such risks dramatically,” it said, after Russian troops took control of the Zaporizhzhia nuclear plant, allegedly shelled the site and occupied the area of the 1986 Chernobyl disaster.
The statement was signed by Mr Ivanov and former UK defence secretary Des Browne, retired German diplomat Wolfgang Ischinger, ex-US energy secretary Ernest Moniz and former US senator and nuclear policy expert Sam Nunn.
Before the invasion, Mr Ivanov and 25 other Russian signatories backed a call for East-West agreements on military drills, missile deployment and regular contacts to lower tension.
The war has scotched hopes of any broad agreement in the short term, but the five foreign policy specialists stated in their letter that diplomacy and dialogue were the “only acceptable way to resolve the conflict” in an enduring way.
It came as Russian and Ukrainian negotiators held a second consecutive day of talks on the 20th day of an invasion that has forced more than three million people to flee the country.
“The first and most essential step toward reducing the risks of a consequential accident, mistake, or miscalculation is a ceasefire to end the unacceptable and unjustifiable loss of human lives, including innocent civilians,” the letter said.
Russia is accused of attacking civilians in what western powers say could amount to war crimes, while the Kremlin’s line is that Ukraine is to blame for using them as human shields. The UN says at least 636 civilians have died during the fighting.
The fighting around the Zaporizhzhia nuclear power plant in Ukraine was “the latest reminder of how nuclear catastrophe can quickly rise to the surface in the ‘fog of war’,” the five statesmen said.
“We must return to diplomacy and dialogue to ensure current disputes on core issues are negotiated and not fought.”
The UN’s nuclear watchdog says reactors are still operating at Zaporizhzhia but that it is investigating reports of Russian munitions exploding at the plant. The Kremlin accuses Ukraine of fabricating the incident.