"Ru sources claim a massive tank led assault is underway in the Orikhiv area towards Tokmak.My speculation:
The assault began late at night.
Details later"
Tokmak is on the route to Melitopol. Taking Melitopol would divide the Zaporizhia Oblast along its narrowest axis. The distance between the Dnipro River and the Molochnyi Estuary is 50 miles/80 km. Russia would lose a direct land connection to Western Zaporizhia, Southern Kherson and Crimea except over the Kerch Bridge. Together with the destruction of the Nova Kakhovka dam cutting off fresh water to Crimea, holding these areas becomes impossible.
Assuming the US and NATO knew in advance, should Ukraine achieve this goal, then they will show they can deliver on what was promised and continue getting aid. It will also show Russia is incompetent militarily and politically, weakening their international standing even more.
Like Kherson and Kharkiv, during the first few days there is the Ukrainian news blackout and Russian disinformation making what is happening unclear. Given the importance of what is happening, it make take several more days for even a small amount of clarity to happen.