Just days after Russia officially announced the annexation of four regions of Ukraine, the Ukrainian military staged its biggest military breakthrough in southern Ukraine since the start of the war, advancing 20 miles as Russian forces carried out a precipitous retreat.

The Ukrainian offensive follows a similar lightning breakthrough in northeastern Ukraine last month, in which the Russian front collapsed in a disorganized rout and Ukrainian forces advanced dozens of miles in the span of days.

Reuters called this weekend’s advance the “biggest breakthrough in the south of the country since the war began, bursting through the front and advancing rapidly along the Dnipro River on Monday, threatening supply lines for thousands of Russian troops.” Reuters added, “Ukrainian troops had advanced dozens of kilometers along the river’s west bank, recapturing a number of villages along the way.”

On Sunday, Ukrainian President Volodymyr Zelensky announced that the strategic town of Lyman had been fully occupied by Ukrainian forces.

“The information is tense, let’s put it that way, because yes, there were indeed breakthroughs,” Vladimir Saldo, the head of the Russian-occupied section of Ukraine's Kherson province, told Russian state television.

Video posted on social media showed dozens of Russian corpses, alongside discarded clothing and equipment. The Ukrainian military claimed it destroyed 31 Russian tanks during the offensive.

Commenting on the significance of the Ukraine victory, the Washington Post noted that “Lyman is a key supply hub on the western edge of Ukraine’s Donbas region, where Russia has concentrated its military campaign for months. Russian forces have used it to supply operations to the east since capturing Lyman in the spring.”

NATO Secretary General Jens Stoltenberg attributed the breakthrough to the “advanced weapons that the United States and other allies are providing,” adding, “This is making a difference on the battlefield every day,” he told NBC.

Stoltenberg is correct. The breakthroughs in the Russian lines were made possible by the advanced weapons systems provided by the United States to Ukraine since April. In particular, Russia has been denied air superiority by the NASAMS anti-aircraft system, and radar installations have been pulverized by the HAARM anti-radiation missile.

This has allowed the American HIMARS system to strike targets unobstructed dozens of miles behind the Russian front, systematically dismantling the Russian logistics and supply system, as well as its command structure, leading Russian troops to effectively melt away before the Ukrainian advances.

“The fact we have broken through the front means that ... the Russian army has already lost the ability to attack, and today or tomorrow it could lose the ability to defend,” Oleh Zhdanov, a Ukraine military analyst, told Reuters.

He continued, “A month of our work destroying their supplies and reducing the combat effectiveness of this group means that they are functioning on minimal rations in terms of ammunition, fuel and food.”

The collapse of the Russian line in southern Ukraine led to a wave of triumphalism among US military figures. Former National Security Advisor H.R. McMaster claimed that the Russian military is at the “breaking point.”

“What we might be at here is really at the precipice of really the collapse of the Russian army in Ukraine. A moral collapse,” McMaster told CBS on Sunday.

A Defense Department official told Politico, however, that such claims were premature, and that as Russian forces retreat to established defensive lines in the Donbas, both sides are likely in for a bloodbath.

“There’s lots of heavy fighting ahead,” the  Defense Department official told Politico. Another added, “It’s important strategically, but they still have a long way to go.”

The disaster has prompted a series of recriminations within the Russian political and military establishment. On Saturday, Chechen leader Ramzan Kadyrov openly criticized the Russian military command, encouraging Russian President Vladimir Putin to use nuclear weapons.

“More drastic measures should be taken,” Kadyrov said,  “up to the declaration of martial law in the border areas and the use of low-yield nuclear weapons.”

Putin confidante Yevgeniy Prigozhin, founder of mercenary group Wagner, said of the Russian military command, “I think that we should send all these bastards barefoot to the front with machine guns.”

Elena Panina, a former lawmaker, commented, “According to numerous estimates, Russia is facing an enemy that is more numerous, better armed, better prepared and better motivated.”

In a further indication of the crisis of the Putin government, the Kremlin’s press secretary Dmitri S. Peskov could not specify the borders of the Russian Federation following the referendums and the military debacle this weekend, declaring, “In terms of the borders, we’re going to continue to consult with the population of these regions.”

The growing crisis for Russia’s armed forces only escalates the danger that the Putin regime, backed into a corner, could use nuclear weapons in the face of battlefield defeats.

The United States is actively making preparations for such a scenario. The New York Times reported on US preparations to respond to a nuclear escalation of the war:

For months now, computer simulations from the Pentagon, American nuclear labs and intelligence agencies have been trying to model what might happen and how the United States could respond. It is no easy task because tactical weapons come in many sizes and varieties, most with a small fraction of the destructive power of the bombs the United States dropped on Hiroshima and Nagasaki in 1945.

In the most troubling development yet, however, the British Telegraph reported potential indications that Russian nuclear forces may be moving toward the front.

The Telegraph reported Monday that a “train operated by the secretive nuclear division and linked to the 12th main directorate of the Russian ministry of defense was spotted in central Russia over the weekend heading towards the front line in Ukraine.”

It cited Polish defense analyst Konrad Muzyka, who wrote that “this is actually a kit belonging to the 12th Main Directorate of the Russian MoD… The directorate is responsible for nuclear munitions, their storage, maintenance, transport, and issuance to units.”

The latest military debacle suffered by Russia only presages a further bloodbath for Ukrainian and Russian forces alike, as Russian forces retreat to well-entrenched positions in the Donbas, and the Ukrainian forces, at the instigation of the US military officers now in full command of the operation, press to retake the entirety of the Donbas and Crimea.