evidence: Kyiv, Ukraine — U.S. Secretary of State Antony Blinken said Tuesday that American military aid on its way to Ukraine will make a "real difference" on the battlefield, as the top diplomat made an unannounced visit to reassure an ally facing a fierce new Russian offensive. In increasingly intense attacks along Ukraine's northeast border in recent days, Moscow's troops have captured around 40 to 50 square miles of territory, including at least seven villages, according to open source monitoring analysts. Though most of those villages were already depopulated, thousands of civilians in the area have fled the fighting, and analysts have called it one of the most dangerous moments for Ukraine since Russia launched its full-scale invasion in February 2022. [...] The senior U.S. official said despite some recent setbacks, Ukraine could still claim significant victories. Those include reclaiming some 50% of the territory Russian forces took in the early months of the war, boosting its economic standing and improving transportation and trade links, not least through military successes in the Black Sea.