invitation of a lifetime. announcer: this is nbc nightly news with lester holt. good evening it s on. a new phase of the war in ukraine. ukraine s president tonight saying russia s battle for donbas is under way. its much anticipated attack deep in the ukraine s east after failing to take the capital, kyiv president zelenskyy declaring, we will defend ourselves. the russians stepping up their aerial strikes today, even hitting targets in the far west city of lviv, killing at least seven people in a city once considered a safe haven. while in the port city of mariupol, a desperate battle rages tonight. the ukrainian military claiming its forces are still holding on in the face of a determined russian assault. the city in ruins. thousands still trapped without food or other essentials ukrainian fighters refusing russia s calls for their surrender. there s a lot to report from there tonight.