On February 4, 2026, the last
remaining nuclear arms control
treaty between the United States
and Russia officially expired,
marking the end of over half
a century of binding limits on
the world’s two largest nuclear
arsenals. This development has
alarmed diplomats, security
experts, and international leaders,
who warn that its timing could

not be worse given rising geopo-
litical tensions and the erosion of

other arms control frameworks.
The treaty in question is New

START, the Strategic Arms Reduc-
tion Treaty, first signed in 2010 by

the U.S. President Barack Obama
and Russian President Dmitry
Medvedev, and later extended
once in 2021. New START placed
legally binding limits on the

number of strategic nuclear war-
heads and delivery systems that

each side could deploy. Specif-
ically, it capped each nation at

1,550 deployed strategic nuclear
warheads and 700 deployed

delivery systems (including inter-
continental ballistic missiles,

submarine-launched ballistic
missiles, and heavy bombers). The
treaty also established detailed

verification mechanisms, includ-
ing on-site inspections, data

exchanges, and notifications to
maintain transparency and build
trust between Washington and
Moscow.
For years, New START was a
cornerstone of nuclear stability,

anchoring the bilateral relation-
ship and helping prevent worst-
case scenarios of miscalculation

or inadvertent escalation between

nuclear superpowers. Its verifica-
tion mechanisms were especially

vital: by allowing each side to see

in detail the other’s strategic arse-
nals, they reduced uncertainty and

built a baseline of mutual predict-
ability that eased fears of surprise

nuclear buildups.
The expiration of New START is
the latest chapter in a long history
of nuclear arms control between
the U.S. and Russia. During the
Cold War, successive treaties,
including START I (1991) and
START II (signed 1993, never
entered into force), were part of
a broader effort to reduce the risk
of nuclear confrontation. START I
alone led to the removal of roughly

80% of all strategic nuclear weap-
ons once in existence.

In the decades that followed,

other agreements like the Strate-
gic Offensive Reductions Treaty

and New START continued this

trend of limiting arsenals and pro-
moting bilateral cooperation. But

starting in the late 2010s, many
of these frameworks unraveled:
the Intermediate-Range Nuclear
Forces Treaty collapsed in 2019
when the U.S. withdrew over
alleged Russian violations, and
other accords quietly faded amid
heightened mistrust.
New START endured longer
than most because it continued

to offer a mechanism for verifi-
cation and restraint, even after

Russia suspended its participation
in verification measures in 2023,
citing geopolitical tensions related
to its war in Ukraine, and the U.S.
responding in kind. Despite the
suspension of data exchanges and

inspections, both sides publicly

claimed adherence to numeri-
cal limits for some time. Without

formal verification, the treaty’s
stabilizing influence eroded.
For the first time since the early
Cold War era, the two countries

with the overwhelming major-
ity of the world’s nuclear weap-
ons are no longer bound by any

bilateral arms control treaty.
International figures from the
UN Secretary-General to nuclear
policy experts have described
this moment as a “grave threat” to
global peace and security, warning
that the absence of limits could
spark a new arms race or allow
miscalculations that increase the
risk of nuclear use.
In the immediate aftermath of
New START’s expiration, both

the U.S. and Russia have indi-
cated a desire– at least rhetor-
ically– to negotiate new arms

control arrangements that might
include other nuclear powers such
as China. Russian officials have
expressed regret that the treaty
expired without an agreement to

extend it, while U.S. policymak-
ers signal that negotiation could

resume if a broader, more inclu-
sive pact is achieved.

Yet, experts caution that
rebuilding trust and negotiating
new restrictions will be far more

difficult than in the past. The polit-
ical landscape has shifted, and

the backdrop of current conflicts
makes cooperation more complex
than during previous periods of
the 1900s. Until a new framework

is established, the world must nav-
igate a nuclear landscape without

the guardrails that defined global
security since the Cold War.
The expiration of the New
START Treaty at such a fraught
juncture represents not just the
end of a historic agreement, but a

pivotal inflection point in interna-
tional security– one that exposes

the fragility of nuclear arms con-
trol in an era of geopolitical com-
petition and uncertainty.