Dozens of pro-Ukrainian fighters claimed on Tuesday to have launched an incursion with tanks and armored vehicles across the border into Russia, in what may be the largest attack over the border since the start of the full-scale invasion in February 2022.
Fighters from two pro-Ukrainian Russian militant groups claimed to have crossed the border this morning into the Belgorod region that border northeast Ukraine and to have engaged Russian forces.
Russia's Ministry of Defense and Federal Security Service, the FSB, confirmed that dozens of fighters tried to break through into the Belgorod and Kursk region farther south.
But the ministry claimed the Ukrainian fighters were "repulsed" after suffering heavy casualties and that they were unable to penetrate into the border regions.
MORE: Russia-Ukraine war: Key events in 2nd year of Russia's invasion of UkraineThe FSB claims "over 100 enemy personnel, six tanks, a Caesar self-propelled gun, [and] 20 armored combat vehicles" were destroyed.
The Free Russia Legion, a group of Russians fighting on behalf of Ukraine, posted a video this morning claiming to show itself moving with tanks moving over the border. It has also posted a video claiming to show a Russian armored vehicle being destroyed in a border village.
The group claimed fighters took control of Tetkino, a village right up against the border in the Kursk region.
Ukraine also launched a massive drone attack against at least 10 Russian territories on Tuesday with some drones reaching deep into Russian territory. Russia's Defense Ministry said air defenses shot down at least 26 Ukrainian drones over seven regions of the country.
The drone attacks were carried out throughout the day Tuesday.
ABC News' Tanya Stukalova contributed to this report.
This is a developing story. Please check back for updates.