The Biden administration has prepared a package of $ 200 million in additional military aid for Ukraine in recent weeks, but has chosen to halt aid delivery despite calls from Kiev and some lawmakers, three people say close to the file.

A source familiar with the matter, however, said there were a number of other options on the table for further aid to Ukraine, including a much larger aid package that would be approved in the event of a further incursion. from Russia.

Earlier this week, National Security Advisor Jake Sullivan told reporters that President Joe Biden told Russian President Vladimir Putin that if Russia launches an attack, the United States will impose tough sanctions on Moscow and send more military aid to Ukraine.

“We would provide additional defensive material to the Ukrainians beyond what we are already providing,” said Sullivan, recounting Biden’s conversation with Putin.

The source familiar with the matter said Sullivan was referring to this much larger potential aid package, not the $ 200 million shipment.

The administration’s decision to delay the smallest shipment of arms and military equipment was designed to give more time to diplomatic efforts to defuse tensions and retain influence in the event of a Russian attack on Ukraine, the three people familiar with the matter told NBC News.

The smaller package “has been on the president’s desk for about three to four weeks,” said one of the sources briefed on the matter.

The smaller $ 200 million package was due to be approved and announced last week, but the White House has instead chosen to postpone any final decision, the sources said.

While it is not clear exactly what is included in the proposed aid of $ 200 million, Ukraine has requested air defense systems, anti-ship missiles, more Javelin anti-tank missiles, electronic jamming equipment. , radar systems, ammunition, improved artillery ammunition and medical supplies, according to two people familiar with the request.

After submitting its urgent request for military assistance a month ago and receiving a positive response, the Ukrainian government wondered why the aid package had not gone as planned. “There is a slight frustration about this,” said a person familiar with the Kyiv government’s point of view.

The White House did not respond to a request for comment. A spokesperson for Ukrainian President Volodymyr Zelenskyy declined to comment.

A bipartisan group of 22 House lawmakers wrote a letter to Biden on Wednesday urging the administration to speed up military aid to Ukraine.

“To maximize deterrence, it is essential that at least one military aid – Stingers, Javelins, drones and anti-ship missiles – be provided immediately. The Ukrainian state must be provided with the necessary tools to defend itself and the region against Russian aggression, ”the lawmakers wrote.

In a comment posted Friday in Foreign AffairsUkrainian Foreign Minister Dmytro Kuleba said it was vital “to deepen military assistance to Ukraine”.

“We have our own capable military forces in Ukraine, and we don’t expect Western countries to put their boots on the ground,” Kuleba wrote. “However, we need more weapons to be able to defend ourselves. Everything from ammunition to medical equipment, but we especially need air and missile defenses.”

Kuleba said only the firm resolve of the United States and NATO will succeed in countering Russia.

“For too long the West has refused to take Putin’s ambitions seriously and has responded with delay, indecision and weakness. It is time to meet them with strength.

The United States is already providing military assistance to Ukraine on an ongoing basis and has provided around $ 400 million so far in 2021, with an additional $ 50 million in reserve, the highest sum in a single year since 2014.

The decision on the timing of any further military assistance to Ukraine reflects a larger debate in Washington on how to prevent Russia from going to Ukraine.

The Biden administration and its supporters believe that a combination of threats of sanctions, military aid and diplomacy can persuade Putin to withdraw the tens of thousands of Russian troops he has deployed along the Ukrainian border.

But skeptics in Congress, including some Democrats, Eastern European government officials, and some former US diplomats, fear the White House has been too cautious in its approach to Russia and avoided taking action. difficult, in particular by sanctioning an almost complete gas pipeline transporting natural gas to Europe. by the Baltic Sea.

Earlier this year, when Russian troops massed near Ukraine, the administration prepared another major military aid package for Ukraine. But officials resisted as Russia downsized its troop presence in April and Moscow and Washington agreed on a summit between Biden and Putin.

Further military aid was not announced until September, when President Zelenskyy met with Biden in Washington.

For the White House, the spring result justified the administration’s approach, defusing tensions while showing determination. For critics, the episode showed that the administration was signaling weakness in Moscow, encouraging greater aggression from Putin.

National Security Advisor Sullivan and his deputy Jon Finer were influential in shaping Biden’s policy in Russia, advocating a flexible approach that at times put them at odds with other officials from administration, according to former officials and representatives of Congress. aids.

Senior State Department officials who supported the imposition of sanctions on Russia’s Nord Stream 2 gas pipeline to Europe were dismissed in May, with the White House wanting to avoid a clash with the German government which supported the pipeline.

The administration said the United States would impose sanctions on the pipeline if Russia invaded Ukraine again.

William Taylor, former US ambassador to Ukraine, said US military assistance was key, along with the threat of severe sanctions and diplomatic dialogue, in repelling a possible Russian offensive in Ukraine.

“The United States should continue and accelerate its military assistance to Ukraine in response to renewed threats to Ukrainian, European and international security,” Taylor said.

The former ambassador said there had been “a good flow of aid since the first Russian invasion in 2014,” including $ 60 million announced in September that was delivered this week.

Ukraine said it was satisfied with a telephone conversation Wednesday between Biden and Zelenskyy, saying the talks reinforced the importance of “deterrence and de-escalation.”