KYIV, Ukraine (AP) — Russian President Vladimir Putin has ordered martial law for four illegally annexed Ukrainian regions, doubling down on a faltering invasion he described as “very difficult.” In a tacit acknowledgment that another stinging battlefield defeat may be unfolding, his forces organized evacuations of civilians from one of the first major cities they seized. With a Ukrainian counteroffensive grinding toward Kherson, the battle for the southern city is a pivotal moment for Ukraine and Russia heading into winter. Russia’s increasingly tenuous hold on Kherson and the wider region of the same name as well as Putin’s martial law order were more signs that the nearly 8-month-old invasion was not going as planned.