reporter: today, more russian troops and hardware arriving in belarus, to ukraine s north, for war games, adding to the pressure from thousands already massing to the east. the kremlin threatening a military technical response unless there s a guarantee ukraine won t join nato. president putin has created this crisis by amassing 100,000 russian troops along ukraine s borders. this includes moving russian forces into belarus recently for joint exercises and conducting additional exercises on ukraine s eastern border. reporter: secretary blinken now en route to the region for talks in ukraine. then a face-to-face with the russians. it could make the difference between war and peace. and ian pannell joins us tonight from ukraine. bipartisan group of senators met with the president of ukraine. they ve now returned to the u.s. and now secretary blinken headed to the region. how confident is the biden administration tonight that they ll be able to reach some sort of an agreement thro