The Biden administration is considering sending military advisers and weapons to assist Ukraine amid the growing threat of Russia invading its Eastern European neighbor, CNN reported Tuesday.

Multiple sources told CNN that discussions about the proposed lethal aid package could include new Javelin anti-tank and anti-armor missiles as well as mortars.

Air defense systems, such as stinger missiles, and some equipment originally targeted for Afghanistan also were under consideration, CNN reported.

Some equipment, such as Mi-17 helicopters, were purchased from Russia and destined for Afghanistan before President Joe Biden’s U.S. troops withdrawal that led to the Taliban quickly taking over the country.

Members of the administration, though, are concerned that sending stingers and helicopters to Ukraine could be seen by Russia as a major escalation, CNN said.

The CNN report also said it was unclear whether any military advisers would be sent to the region or directly to Ukraine.

Retired Col. Cedric Leighton told CNN that Javelin anti-tank missiles “are quite effective against the T-80 tanks which the Russians are actually employing in these efforts against Ukraine right now.”

Ukraine has warned that Russia could invade as soon as January. U.S. officials believe that Russia President Vladimir Putin could be determined to keep Ukraine from growing closer to the West and potentially joining NATO, CNN said.

The Kremlin on Monday strongly rejected U.S. claims of a Russian troop buildup near Ukraine, saying it could be a ruse intended to cover up what it described as Ukrainian leadership’s aggressive intentions.

Administration officials also have talked with European allies about a new sanctions package that would go into effect if Russia invaded Ukraine, CNN sources said.

The U.S. has been sharing intelligence with NATO partners and European allies on unusual Russian troop movements near the Ukrainian border. Military and intelligence officials believe Russia’s actions could be a precursor to a military operation on the country’s eastern flank, CNN reported.

U.S. officials and lawmakers are concerned about the possibility of Russia invading Ukraine, a strategic U.S. ally, for the second time in less than a decade, CNN reported.

“Our concern is that Russia may make a serious mistake of attempting to rehash what it undertook back in 2014, when it amassed forces along the border, crossed into sovereign Ukrainian territory and did so claiming falsely that it was provoked,” Secretary of State Antony Blinken said last week, CNN reported.

The Associated Press contributed to this story.