Welcome to the News Hour. For the first time in more than a half century, there are no limits on the

world's two largest atomic arsenals. The sole remaining nuclear arms treaty in the world,

known as New Start, is expiring, and arms control advocates fear a new arms race. Nick Schiffran

starts our coverage.

They're the world's deadliest weapons, able to obliterate entire cities.

And when mounted on missiles, can fly thousands of miles in minutes. And for the last 15 years, the deployment of Russian and American long-range nuclear weapons

has been restricted. Today is an important milestone for nuclear security and nonproliferation.

It was 2010 when President Barack Obama and then Russian President Dmitri Medvedev

signed the new Strategic Arms Reduction Treaty.

It limited the U.S. and Russia to 700 deployed intercontinental ballistic missiles on land, at sea,

and on heavy bombers. And it limited to 1,550 the number of deployed nuclear warheads.

It also included extensive verification measures, such as movement notifications, data exchanges, and on-site inspections, although the

inspections stopped during COVID and never resumed.

That the New START treaty is in the national security interests of the United States.

In 2021, the U.S. and Russia agreed to extend the treaty for another five years until today.

Last year, Russian President Vladimir Putin offered to extend it further into next year.

In the past, the New START Treaty worked.

It worked well, fulfilling its fundamental role as a constraint, curbing the arms race and

controlling weapons.

But today in Washington, Secretary of State Marco Rubio said new start was no longer fit for purpose.

In order to have true arms control in the 21st century, it's impossible to do something that doesn't include China because of their vast and rapidly growing stockpile.

For years, China's stockpile has been a fraction of the U.S. and Russian stockpile, what

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