The announcement comes as Congress has yet to pass new aid for Ukraine since December.

President Joe Biden, accompanied by Polish President Andrzej Duda and Prime Minister Donald Tusk, stated that the package includes urgently required munitions and rounds to help Ukraine defend itself against Russia's brutal attacks in the next few weeks.

During a White House briefing, National Security Adviser Jake Sullivan emphasized that Ukraine is currently facing a shortage of ammunition to defend itself. He revealed that the emergency assistance comprises anti-aircraft missiles, ammunition, artillery rounds, and anti-armor systems. Sullivan stressed that Ukraine desperately needs this assistance to hold the line against Russian attacks and push back against the continued onslaught in the Eastern region and other areas.

Responding to a question about the speed of the aid's delivery, Sullivan assured reporters that the White House has the logistical capability to swiftly transport the support to Ukraine. He cited their proven track record and expertise in moving military supplies, noting that while he couldn't provide a precise estimate for operational reasons, the aid would be delivered rapidly.

The announcement of this emergency funding comes as a $95 billion foreign aid package, including nearly $60 million for Ukraine, has been stalled in the House for almost a month. The bill was passed by the Democrat-controlled Senate in early February but has not been brought to the floor for a vote by House Speaker Mike Johnson.

Sullivan mentioned that the new aid package benefits from negotiated cost savings from past contracts, allowing for the allocation of this immediate security assistance without impacting U.S. military readiness. He clarified that this emergency package does not replace the need for additional funding that would require congressional action.

One official described this aid package as a "one-time shot," underscoring that the administration does not anticipate a similar opportunity in the future. Sullivan confirmed that future drawdowns based on cost savings were not part of their plans.

The White House has taken this decisive action to assist Ukraine in its defense against Russian aggression while urging Congress to pass the bipartisan national security bill without further delay.

It remains to be seen how quickly this aid will reach Ukraine and how it will impact the ongoing crisis in the region. As developments unfold, the international community will closely watch the situation and assess the effectiveness of this emergency assistance.

ABC News' Alexandra Hutzler contributed to this report.