While Ukrainian forces were secretly planning a counteroffensive to expel occupying Russian soldiers from the northeastern Kharkiv region, Moscow was so certain of its hold on the territory that it began imposing Russian curriculum in local schools.

After regaining control of the land and schools in recent days, and with Moscow’s annexation plans thwarted for the time being, Ukraine said it had arrested Russian teachers who had been left behind by retreating Russian soldiers.

Moscow acknowledged the arrests of educators, but claimed they were Ukrainian collaborators, not Russian citizens. According to the department’s Telegram channel, the head of the Russian Investigative Committee, a top law enforcement body, ordered its own criminal investigation into the arrest of the teachers by the Ukrainians on Tuesday, demonstrating the Kremlin’s reality-bending claim of authority in the region.

It was unclear how many teachers Ukraine had detained, but the arrests were part of the ongoing fallout from Ukraine’s successful operation and Russia’s swift and humiliating retreat.

With the Kremlin under pressure to explain the losses and rare public assertions in Russia that the country’s military effort has been insufficient, President Vladimir Putin’s spokesman reiterated Tuesday that no general military mobilization was planned.

“At the moment, no, it’s out of the question,” spokesman Dmitry Peskov said during a press conference.

Peskov also issued a warning to Putin’s critics, including war supporters who have advocated for a general mobilization and tougher strikes on Ukraine. The Kremlin has made criticizing the war, which it refers to as a “special military operation,” illegal, and has cracked down on dissenters.

“As for other, critical points of view, this is pluralism as long as they remain within the framework of current legislation.” But the line is razor thin,” Peskov cautioned. “You have to be very careful here,” he said, adding that “Russians clearly support the president.” The mood of the group confirms this.

The mood in Russia, on the other hand, has been gloomy, in stark contrast to the joy in Ukraine in recent days, as evidenced by videos of happy residents hugging Ukrainian soldiers as they swept into villages, towns, and strategic cities across the Kharkiv region.

As Kyiv reasserted control over those liberated towns and villages, the Kremlin’s plans for annexing the territory became clearer, from shaping what young Ukrainians learned in school to organizing sham referendums.

It has also revealed Russia’s unpreparedness for Ukraine’s advance, leaving behind not only sympathetic educators but also so many weapons and equipment that military experts believe Russia will now struggle even more to capture any more ground than it currently occupies.

Russia has delayed plans to hold referendums in occupied southern Ukraine, amid a slower-moving separate Ukrainian counteroffensive, which would be illegal and not recognized by the international community, but Moscow planned as a precursor to annexation.

Ukrainian Deputy Prime Minister Iryna Vereshchuk said Monday that the Russian teachers could face up to 12 years in prison for violating war laws and customs, but she did not say how many had been arrested.

Russia has recently promised hundreds of teachers’ large pay raises to go to occupied Ukraine and teach the Russian curriculum — with Russia’s take on Ukraine’s history — in the coming school year.

Russian Education Minister Sergei Kravtsov said at a meeting of Putin’s United Russia party on June 28 that Ukrainian education “must be corrected.” Teachers in the occupied southern region of Ukraine have insisted on using only Russian in class.

However, as some of Russia’s overzealous invasion and annexation plans unravel in the sixth month of the war, Putin is facing increasing domestic pressure.

The initial goals of what the Kremlin refers to as a “special military operation” were to seize Kyiv and impose a regime change. After less than two months of fighting, that failed.

Russia’s 1st Guards Tank Army, one of the most prestigious units in the Russian military, was one of the forces that withdrew from the Kharkiv region and has been “severely downgraded” after suffering “heavy casualties” earlier in the war, according to British intelligence.

“Russia’s conventional force designed to counter NATO has been severely weakened,” the intelligence agency tweeted. “It will most likely take Russia years to rebuild this capability.”