WASHINGTON – The White House announced a new $1 billion military aid package for Ukraine Wednesday – and revealed the Pentagon quietly sent Kyiv controversial long-range missile systems capable of striking deep behind Russia’s frontlines earlier this month.

Minutes after signing a long-delayed $95 billion foreign assistance supplemental bill into law, President Biden promised that aid would begin rolling to Ukraine within “a few hours.”

Moments later, the Pentagon released an announcement detailing the critical weapons and military equipment it was sending to the besieged country.

While most of the equipment in the initial package fulfills basic military needs — and includes anti-aircraft missiles, small arms, artillery rounds, and night vision gear — national security adviser Jake Sullivan revealed that the US had quietly sent Ukraine Army Tactical Missile Systems (ATACMS) weeks ago, despite the White House saying there was no funding left for such assistance.

GOP leaders had successfully advocated for ATACMS to be included in future packages if the supplemental passed, senior House Republican staff told The Post last week.

Biden had previously been hesitant to send the impressive weapons to Ukraine, partly due to fears of escalating the fight.

Moscow’s troops had gained the upper hand on the battlefield in recent months, taking more territory and sneaking more missiles past Kyiv’s air-defense systems as Congress tussled over the supplemental funding package, which Biden first requested in October.

“You can measure the impact [of the funding delay] in different ways. With respect to actual territory, we’re talking about tactical losses in the east, not some fundamental structural shift in the underlying dynamic in the conflict,” Sullivan told reporters at the White House.

“But you can also measure it just in terms of the the wear and tear in places on a frontline unit who has to ration ammunition, because they’re not getting the steady flows,” he added.

The package announced Wednesday also includes Bradley fighting vehicles, Humvees, Claymore mines, MRAP vehicles, and Javelin surface-to-air missiles.

While Ukraine still seeks other capabilities, such as more Patriot missile batteries, the lower-budget items such as artillery shells and spare parts to get weapons back on the battlefield will be welcomed by Kyiv’s forces.

When The Post visited Ukrainian troops at the front last month, an infantry unit commander had said the shortage had become so drastic they had rationed their artillery, only firing on the enemy if there was a large group gathered together.

“Ukraine’s long-range capabilities, artillery, and air defense are critical tools for restoring just peace sooner,” Ukrainian President Volodymyr Zelensky said in a post to X. “I am grateful to all Americans who continue to support Ukraine and recognize that the historical significance of this bill extends beyond politics.”

“This vote [to approve the supplemental] reinforces America’s role as a beacon of democracy and the leader of the free world,” he added.

Wednesday marked the 56th tranche of military equipment the Pentagon has sent Ukraine since the fall of 2021, when Russian President Vladimir Putin began preparing for his invasion launched on Feb. 24, 2022.

It typically takes the Pentagon no more than four days to deliver a new weapons package, meaning the equipment could be in Ukrainian hands by Monday.