U.S. promises Ukraine $1B more in weapons. This is what it's for.

Mykolaiv, Ukraine — The Biden administration announced on Monday its largest single military package yet for Ukraine, pledging another $1 billion in rockets, ammunition and other equipment. Announcing the drawdown from the U.S. military's stocks, Secretary of State Antony Blinken praised the Ukrainians for already using such weapons "so effectively to defend themselves" amid Russia's assault.

But as CBS News senior foreign correspondent Charlie D'Agata reports from the key port city of Mykolaiv, Ukraine's defenders say they need more, and fast. The message from the Ukrainian general tasked with keeping the city out of Russian hands as it braces for an expected showdown was unambiguous: If they stand any chance of fighting back, they need more firepower.

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Major General Dmytro Marchenko spoke to D'Agata in the rubble of the regional government headquarters. He and his troops are hoping to stage a counter offensive, but none of them need reminding that Russia has the upper hand when it comes to heavy weapons.

Marchenko told CBS News that for every 100 shells the Russians fire at the city, his forces can respond with only 10.

But the Kremlin's forces are running out of precision-guided missiles they used to raze buildings in Mykolaiv in the spring, during the early days of the war.

The general listed the weapons the city's people and infrastructure are now facing, from long-range missiles to Soviet-made rockets from the 1960's — even anti-aircraft munitions and cluster bombs.

Marchenko credited American-supplied, advanced HIMARS multiple-launch rocket systems for helping his forces strike weapons depots and sever supply lines far behind the Russian front lines. More HIMARS rockets were among the items promised by Washington on Monday.

The general called the HIMARS "one of the main factors" behind his troops' ability to hold their ground so far, and to start seeking an advantage on the battlefield.

But the Russian onslaught has been relentless. The front-line town of Bakhmut, hundreds of miles east of Mykolaiv, has suffered ferocious bombardment.

The incessant shelling of the eastern Donbas region's main water supply has left residents in the city of Sloviansk without water for two months, adding to the suffering in cities under siege.

Mykolaiv is also bombed every night. It was hit again Monday night and early Tuesday morning, and D'Agata and his team could hear the explosions in the distance.

General Marchenko said it happens three times a day, and the bombs strike at random, hitting civilians homes, and even hospitals.

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