Nuclear threat rising? Putin says Russia won't cooperate with last remaining nuclear treaty with US

 Russia is "suspending" its participation in the New START nuclear nonproliferation agreement, an ominous development as Russia faces heavy losses in its war with Ukraine.

Russian President Vladimir Putin announced in a speech Tuesday that Russia will no longer cooperate with the terms of the nuclear treaty, the last remaining such agreement between Moscow and Washington. Putin blamed the U.S. for a breakdown in relations with the U.S.

"Our relations have degraded, and that's completely and utterly the U.S.'s fault," Putin said.

Putin also claimed that the U.S. government is working on developing nuclear weapons and is considering restarting nuclear testing, which is not true.

"In this situation, [Russia's state nuclear corporation] and the Defense Ministry must ensure readiness for Russian nuclear weapons tests," he said. "We naturally won't be the first to do it, but if the U.S. conducts tests we will also do it. No one should have dangerous illusions that the global strategic parity could be destroyed." 

More from the Associated Press:

The New START treaty, signed in 2010 by U.S. President Barack Obama and Russian President Dmitry Medvedev, limits each country to no more than 1,550 deployed nuclear warheads and 700 deployed missiles and bombers. The agreement envisages sweeping on-site inspections to verify compliance. Just days before the treaty was due to expire in February 2021, Russia and the United States agreed to extend it for another five years.

In response, Secretary of State Antony Blinken condemned Putin's decision as "deeply unfortunate and irresponsible," and promised the U.S. government would be "watching carefully to see what Russia actually does."

The alarming announcement comes one day after President Joe Biden made a surprise visit to Kyiv. His secret trip, in which he declared that "Kyiv stands," came just days before the one-year anniversary of Russia's invasion of Ukraine. 

The Ukraine war has only grown more intense as Russia forces continue to suffer heavy losses in eastern Ukraine.

Importantly, as the New York Times noted, the New START treaty does not cover tactical nuclear weapons known as "battlefield nukes." Putin has seemingly threatened to use them in Ukraine, and Tuesday's announcement could be a signal that Russia is increasingly weighing its nuclear options.