Russia did not agree to Saudi Arabia's proposal to reduce output so Saudi Arabia are now turning up the faucets to pressure Russia into a deal. Saudi Arabia has no intention starting a price war with US shale producers, this is pure tactics to make Russia agree to an output deal.
The United States has a net export of around 0 barrels, meaning that it is neither an importer nor an exporter of oil today. So macroeconomically the US should be more or less unaffected on an aggregated level.