A woman reacts at the scene of a building damaged after recent Russian missile strikes in Pokrovsk, Donetsk region, Ukraine on Wednesday. Libkos via Associated Press

KYIV, Ukraine — Ukrainian authorities ordered a mandatory evacuation Thursday of nearly 12,000 civilians from 37 towns and villages in the eastern Kharkiv region, where Russian forces reportedly are making a concerted effort to punch through the front line.

The local military administration in Kharkiv’s Kupiansk district said residents must comply with the evacuation order or sign a document saying they would stay at their own risk. Ukrainian Deputy Defense Minister Hanna Maliar had said the previous day that “the intensity of combat and enemy shelling is high” in the area.

The city of Kupiansk and the territories around it were under Russian occupation until September 2022, when Ukrainian forces conducted a rapid offensive operation that dislodged the Kremlin’s forces from nearly the entire Kharkiv region.

The retaking of those areas strengthened Ukraine’s arguments that its troops could deliver more stinging defeats to Russia with additional armament deliveries, which its Western allies duly provided. But as Ukraine has pursued a slow-moving counteroffensive in recent weeks, Russian forces have struck back in some areas.

Maliar said Russia “has formed an offensive group and is attempting to move forward” in the area in an effort to advance on the Ukrainian-held city of Kupiansk, an important rail junction.

It was not possible to independently verify either side’s battlefield claims.

Earlier Thursday, Russian air defense systems on Thursday shot down two drones heading toward Moscow for a second straight day, officials said. The reported attack disrupted flights at two international airports as Ukraine appeared to step up its assault on Russian soil.

One drone was downed in the Kaluga region southwest of Moscow and another near a major Moscow ring road, according to Moscow Mayor Sergey Sobyanin and the Russian Defense Ministry, which blamed the attack on Ukraine.

No casualties or damage were immediately reported.

Ukrainian soldiers sit inside a self-propelled howitzer at the front line in Donetsk region, Ukraine on Wednesday. Libkos via Associated Press

Domodedovo airport, south of the city, halted flights for more than two hours, and Vnukovo airport, southwest of the city, stopped flights for more than two and a half hours, according to Russian news agencies. Ten flights were diverted, Russia’s Federal Agency for Air Transport said.

Firing drones at Moscow after more than 17 months of war has little apparent military value for Ukraine, but the strategy has served to unsettle Russians and bring home to them the conflict’s consequences.

Kyiv officials, as usual, neither confirmed nor denied Ukraine’s possible involvement in the drone strikes, though Air Force spokesman Yurii Ihnat remarked: “This cannot but please us because people in Moscow thought they were safe. Now, the war affects each and every Russian.”

“We now see that ‘something’ happens in Moscow on a regular basis,” he added.

Russia’s Defense Ministry also said it had stopped Ukrainian drone attacks in Moscow-annexed Crimea. It said it shot down two drones near the port city of Sevastopol and electronically jammed nine that crashed into the Black Sea.

The Pentagon is to provide Ukraine with another $200 million in weapons and ammunition to help sustain the counteroffensive, according to U.S. officials.

In this photo provided by the Zaporizhzhia administration Press Office, rescuers work on the scene of a building damaged after Russian missile strikes in Zaporizhzhia, Ukraine on Wednesday. Zaporizhzhia Administration Press Office via Associated Press

Ukraine has already received more than $43 billion from the U.S. since Russia invaded last year.

Ukraine’s presidential office said at least six civilians were killed and 27 were injured between Wednesday and Thursday mornings.

In eastern Ukraine’s Donetsk province, Russia shelled 16 cities and villages, and three people were killed, the office reported. In Zaporizhzhia, three people were killed and nine wounded, including an 11-month-old baby.

Meanwhile, 12 people remained missing after an explosion Wednesday at a factory that makes optical equipment for Russian security forces, Russian state news agency RIA Novosti reported, citing emergency officials.

Russia’s Emergency Ministry said 71 people required medical assistance after the explosion.

Russian officials did not offer a suspected cause of the explosion at the Zagorsk plant in the region around Moscow, which added to jitters about potential Ukrainian drone strikes.

The fallout from Russia’s war against Ukraine has brought concerns to neighboring countries, including the presence of Russia-linked Wagner group mercenaries in Belarus this summer after their short-lived mutiny in Russia.

Poland’s defense minister said Thursday that the country intends to put 10,000 soldiers along its border with Belarus amid fears of a spike in illegal immigration.

Polish officials have accused Belarusian authorities of organizing illegal border crossings to disrupt and pressure Warsaw, which along with other NATO countries has provided support for Kyiv’s war effort.

Associated Press Writer Yuras Karmanau in Berlin contributed to this report.