Ukrainian President Volodymyr Zelenskyy said Monday that Ukraine was ready to accept a ceasefire covering energy targets, but Russia must observe it too. He said Ukraine would respond if Moscow did not honor the arrangement announced by U.S. President Donald Trump on Sunday.

Trump said both sides had agreed to an immediate energy ceasefire. Zelenskyy accused Russia of already violating it, saying Russian drones were entering the skies over Kyiv and other Ukrainian cities on Monday morning.

Naftogaz, Ukraine’s state-owned energy company, said a drone struck its gas production infrastructure in the Kharkiv region overnight. The company reported damaged equipment and a fire, but no injuries. Zelenskyy also reported an attack on a power plant in Kharkiv on Sunday.