Joe Biden is reportedly holding off on delivering military assistance to Ukraine as Russia prepares for what many experts believe is a likely invasion that could happen at any moment.

“The Biden administration prepared a $200 million package of additional military assistance for Ukraine in recent weeks but held off on delivering the aid despite appeals from Kyiv and some lawmakers,” NBC News reported. “The administration’s delay of the smaller shipment of weapons and military equipment was designed to give more time for diplomatic efforts to defuse tensions and to retain leverage in the case of a Russian attack on Ukraine.”

A source claimed to the network that the administration was considering a larger package that would be approved “in the event of further incursion by Russia.” The package has been on Biden’s desk for roughly a month while Russia has amassed tens of thousands of troops near the Ukrainian border.

“Although it’s unclear what the proposed $200 million aid package includes, Ukraine has asked for air defense systems, anti-ship missiles, more Javelin anti-tank missiles, electronic jamming gear, radar systems, ammunition, upgraded artillery munitions and medical supplies,” the report added. “The Biden administration and its supporters believe a combination of threatened sanctions, military aid and diplomacy can persuade Putin to pull back the tens of thousands of Russian troops that he has deployed along Ukraine’s border.”

Ukrainian Foreign Minister Dmytro Kuleba wrote in an op-ed on Friday that the West needed to show more strength in standing up to Russian President Vladimir Putin.

Kuleba wrote that the U.S. and allies needed to send clear political signals to Moscow, threaten severe economic consequences if Russia invades, and “deepen military assistance to Ukraine.”

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

Officials from the U.S. and Ukraine have estimated that Russia currently has between 70,000 and 94,000 troops near the border and that Putin will increase that number to approximately 175,000.