Ukrainian officials say troops from the country’s northern neighbor of Belarus, which has been a strong ally of Russia, have joined in the invasion Russia launched last week.

The alleged invasion was announced on social media by official Ukraine accounts.

“Belarusian troops have entered Chernihiv region. The information was confirmed to the public by Vitaliy Kyrylov, spokesman for the North Territorial Defense Forces. More details later,” a tweet Tuesday from Ukraine’s parliament said, according to Politico

Ukraine’s embassy in Belarus shared a post from the nation’s Centre for Strategic Communications and Information Security on Sunday that read, “Intelligence data confirm the presence of 150 transport helicopters, a large number of Russian troops with several hundred vehicles in several regions of the Republic of Belarus. We urge the international community not to forget that 🇷🇺is not the only one waging war against UA.”