Speaking about Russia’s large-scale attack on Ukraine on 29 December, US President Joe Biden has emphasised that Congress must act quickly to approve more aid for Kyiv.
Source: European Pravda with reference to the White House
Details: The American president stressed that the most recent Russian attack is “a stark reminder to the world that, after nearly two years of this devastating war, Putin’s objective remains unchanged. He seeks to obliterate Ukraine and subjugate its people.”
Well the tanks sold without congressional approval is legally questionable, but not like Congress is going to investigate him over it.
"Under the Arms Export Control Act of 1976, Congress had the power to block an arms sale if both chambers passed resolutions of disapproval within 30 days. "
So Congress doesn’t approve sales but they have the right to block them.
“A Supreme Court decision in 1983 had resulted in a change to the arms export law that required that both chambers pass a joint resolution and send it to the President for enactment. This change raised the bar for successful action by Congress significantly, as the President would likely veto any such resolution. Predictably, President Trump did so, and the Senate could not muster the two-thirds majority needed to override his veto.”
https://democracyjournal.org/magazine/71/arms-sales-the-case-for-affirmative-congressional-approval/