Latvia, a North Atlantic Treaty Organization (NATO) member, has started installing “dragon’s teeth,” which are anti-tank concrete pyramids, along its border with Russia. This is part of an effort to defend the country as tensions rise with Moscow over the war in Ukraine. A video circulating social media on Wednesday, July 24, appears to show the barriers being installed.

Anton Gerashchenko, a former adviser to Ukraine’s minister of internal affairs, shared the footage on X.

“Latvia has started installing defensive barriers on its border with Russia,” he wrote. “The so-called ‘dragon’s teeth’ were spotted near the easternmost Latvian town of Zilup.”

Dragon’s teeth were first used in WWII as a defense against approaching tanks. Latvia’s ongoing efforts to put the concrete pyramids along the border is part of a plan Latvia, Lithuania and Estonia agreed to earlier this year: to build a common defense line with “anti-mobility infrastructure elements.”

With the effort to bulk up NATO’s eastern border with Russia and Moscow’s ally Belarus now underway, Latvia’s Ministry of Defense said that it will help with NATO’s “collective defense.”

Tensions between the Kremlin and NATO were not particularly friendly before Russia’s invasion of Ukraine and the relationship is only getting worse. Moscow said NATO nations are directly involved in the war in Ukraine because the organization provides military aid and weapons to Kyiv. Russia has previously said it may strike NATO members who are helping Ukraine.

Meanwhile, Poland’s defense minister also expressed concerns that Moscow could attack within his country’s borders. However, he still maintained confidence in NATO’s defense capabilities.

Latvia’s move to use decades-old technology to defend its border is not unheard of, with Ukraine’s use of 50-year-old propeller-driven planes to take out Russia’s unmanned aerial vehicles (UAVs). Kyiv also equipped advanced drones with medieval-style caltrops to disable Russian vehicles and to disrupt supply efforts.