An airman loads weapons cargo bound for Ukraine onto a C-17 Globemaster III on Sept. 14, 2022, during a security assistance mission at Dover Air Force Base, Del. (Marco A. Gomez/U.S. Air Force)

WASHINGTON — Congress on Friday signed off on a $12.3 billion aid package for Ukraine that allocates funding for U.S. military operations in Europe, continues weapons deliveries to Kyiv and provides assistance for a potential nuclear incident on the Continent as Russia moved to annex Ukrainian territory.

The third supplemental assistance package approved by Congress for Ukraine contains $7.5 billion in military support and $4.5 billion in economic and humanitarian aid to prop up the embattled country’s government services. It follows a $13.6 billion aid bill for Ukraine in March and a $40 billion assistance package in May that was designed to last until September.

“We cannot stop now and we’re not going to,” Senate Majority Leader Chuck Schumer, D-N.Y., said Thursday, crediting American weapons for helping Ukraine recently regain Russian-held territory in the northeast part of the country and “turn the tide of the war.”

Minority Leader Mitch McConnell, R-Ky., said Ukrainian troops need more High Mobility Artillery Rocket Systems, known as HIMARS, and tanks, fighting vehicles, longer-range rockets, air defense systems, drones and training to operate Western fighter aircraft.

“Assisting Ukraine is not some feel-good symbolic gesture. It is literally an investment in our own national security and that of our allies,” he said. “Blunting [Russian President Vladimir] Putin’s offensive in Ukraine will diminish his capacity to threaten other targets throughout the free world.”

The Senate approved the funding measure on Thursday by a vote of 72-25 and the House backed the legislation on Friday with a 230-201 vote. It is attached to a stopgap government funding bill that lawmakers had to pass to avoid a government shutdown on Friday and fund federal agencies through Dec. 16.

The supplemental funding for Ukraine adds $3 billion to the Ukraine Security Assistance Initiative, a program created shortly after Russia’s first invasion of eastern Ukraine in 2014. The initiative allows the Pentagon to purchase weapons and equipment for Ukraine’s armed forces and pay for training, logistics support, supplies, services, salaries and stipends.

Another $1.5 billion will be spent on replenishing U.S. stocks of weapons delivered to the battlefield while $540 million will go toward increasing production of critical munitions for the U.S. and countries that contributed to the defense of Ukraine at the request of the United States.

The bill also authorizes President Joe Biden to pull up to $3.7 billion in security equipment from U.S. stockpiles, an authority that he has used 21 times since August 2021.

Lawmakers earmarked $2 million for the Pentagon’s inspector general to keep tabs on the aid surging into Ukraine and are requiring a certification by the Secretary of State that protects against corruption.

Rep. Rosa DeLauro, D-Conn., chairwoman of the House Appropriations Committee, said Friday that the safeguards will “ensure weapons are used for their intended purpose by their intended recipients.”

Nearly $3 billion in appropriated funds will flow to U.S. European Command, which has provided mission and intelligence support to Ukrainian forces beating back Russia’s invasion. The funds will also cover special duty pay for U.S. troops deployed to Eastern Europe to bolster NATO’s eastern flank.

The supplemental package notably provides $35 million to the National Nuclear Security Administration to “prepare for and respond to potential nuclear and radiological incidents in Ukraine.” Putin raised the specter of a nuclear strike earlier this month when he announced the mobilization of hundreds of thousands of Russian reservists for the war effort.

“In the face of a threat to the territorial integrity of our country, to protect Russia and our people, we will certainly use all the means at our disposal,” he warned. “This is not a bluff.”

Putin on Friday proclaimed the annexation of four Ukrainian regions partially occupied by Russian troops. The regions — Donetsk, Luhansk, Zaporizhzhia and Kherson — held Kremlin-orchestrated referendums during the last week to join Russia, with residents casting ballots at gunpoint, according to the State Department.

The “spectacle” of voting was denounced by Secretary of State Antony Blinken on Thursday as a “futile effort to mask what amounts to a further attempt at a land grab in Ukraine.” Russia illegally annexed Ukraine’s Crimean Peninsula in 2014 and recognized Donetsk and Luhansk as independent states shortly before launching a full-scale invasion of Ukraine in February.

The U.S. announced new sanctions Friday in response to Russia’s actions, condemning them as violations of international law that trampled on the U.N. Charter and showed contempt for peaceful nations.

“We will continue to provide Ukraine with the equipment it needs to defend itself, undeterred by Russia’s brazen effort to redraw the borders of its neighbor,” Biden said in a statement. “I look forward to signing legislation from Congress that will provide an additional $12 billion to support Ukraine.”

The third supplemental aid package brings the total amount of aid Congress allocated for Ukraine this year to more than $65 billion. The bill falls slightly short of the White House’s request, however, which called for $13.7 billion to sustain the pace of assistance to Ukraine through the end of the year.