The United States is preparing to announce another $275 million in military aid for Ukraine, including much-needed artillery and ammunition as Ukrainian forces struggle to stop the slow advance of Russian forces in the country’s east. The Pentagon will formally announce the package on Friday, according to officials who spoke on condition of anonymity. The aid includes High Mobility Artillery Rocket System (HIMARS) munitions, artillery rounds and anti-tank mines, among other items. This new package will be authorized under Presidential Drawdown Authority, which allows President Joe Biden to tra…