U.S. President Joe Biden has approved the delivery of anti-personnel landmines to Ukraine, a U.S. defense official told the BBC. The decision is seen as an effort to slow Russian advances in Ukraine’s eastern regions, where fighting has intensified in recent months.

Speaking anonymously, the official said the mines would be sent soon and would be deployed within Ukraine’s borders. Ukraine has assured the U.S. that the mines will not be used in densely populated areas, according to the official.

In a separate development, the U.S. State Department announced the temporary closure of its embassy in Kyiv due to a “specific” threat of a significant air attack on November 20. Embassy staff were instructed to shelter in place, and U.S. citizens in Ukraine were advised to be prepared for immediate action in case of air alerts. The embassy has issued similar warnings around New Year and Ukraine’s Independence Day in the past.

Following the U.S. announcement, the Italian and Greek embassies also temporarily closed operations in Kyiv. Meanwhile, Ukraine’s defense intelligence agency claimed that rumors of large-scale missile strikes were part of a Russian “information and psychological attack” and urged citizens to rely on official sources and heed air raid warnings.

Both Ukraine and Russia reported major drone attacks overnight, though details about casualties remain unclear.

The supply of anti-personnel landmines marks another significant step by the Biden administration to bolster Ukraine’s defenses before the anticipated transition of power to Donald Trump on January 20. For Ukrainian forces facing Russian advances along a vast eastern front, the mines are seen as essential.

Russian tactics have included sending small units—sometimes just a few soldiers or motorcyclists—behind Ukrainian positions. Ukrainian analysts report that in areas like Chasiv Yar and Kurakhove, Russian troops are sent out in waves every 20 minutes, creating ongoing challenges for Ukrainian defenders.

Serhiy Kuzan of the Ukrainian Security and Cooperation Centre emphasized the need for more mines to counter these tactics. Much of the fighting is occurring in rural Donbas, where wooded areas are interspersed with open farmland. Ukraine argues that using “non-persistent” mines in evacuated regions minimizes civilian risks while addressing the urgent need to slow Russian advances.

Russia has extensively used landmines throughout the conflict, but international objections to their risks for civilians had previously delayed U.S. approval for their use. Unlike Russian mines, U.S. “non-persistent” mines deactivate after a set period—ranging from four hours to two weeks—using battery-powered electrical fuses. Once the batteries deplete, the mines become inert.

The U.S. has already provided anti-tank mines to Ukraine, but the new anti-personnel mines are designed for rapid deployment to disrupt ground troop movements. Neither the U.S. nor Russia are signatories of the Ottawa Convention banning anti-personnel landmines, though Ukraine is. However, more than 20% of Ukraine’s territory has been contaminated by mines since Russia’s full-scale invasion began in February 2022.

Additionally, it was recently confirmed that Ukraine used U.S.-supplied long-range Army Tactical Missile System (ATACMS) missiles to strike targets inside Russia. A Russian military facility in the Bryansk region was reportedly hit, with Russia claiming it intercepted most of the missiles. However, U.S. officials suggested that Russia had intercepted only two out of eight missiles.

Russian Foreign Minister Sergei Lavrov accused the U.S. of escalating the conflict, and the Kremlin has vowed to respond.