The White House has rejected Russian President Vladimir Putin’s proposal to extend the New START nuclear treaty for one year unconditionally, reported AFP. According to AFP, the US said that both nations must cap warheads during the period.

“President Putin’s response today to extend New START without freezing nuclear warheads is a non-starter,” said Robert O’Brien, the national security advisor.

He said the US had already given time to negotiate beyond the treaty’s scheduled expiration in February — with the understanding that the world’s two biggest nuclear powers would freeze warhead work in the interim period.

“This would have been a win for both sides, and we believed the Russians were willing to accept this proposal when I met with my counterpart in Geneva,” O’Brien said in a statement on Twitter.

The last major nuclear reduction treaty between the US and Russia, New START, limits each country to 1,550 nuclear warheads. The US negotiator, Marshall Billingslea, said earlier this week that Russia had agreed to a freeze during a temporary extension but Moscow issued a denial.

“The United States is serious about arms control that will keep the entire world safe. We hope that Russia will re-evaluate its position before a costly arms race ensues,” he said.

If President Donald Trump loses the November 3 election, New START would expire days into the term of Joe Biden, who supports an extension.

The United States had been holding out without success for China — whose nuclear arsenal is rapidly growing but still far smaller than those of the US and Russia — to enter negotiations on an expanded, three-nation deal.