"I count on the House of Representatives to agree support to Ukraine, because this is not charity. This is an investment in our own security," Stoltenberg, Secretary General of the North Atlantic Treaty Organization, told Reuters in an interview.
Stoltenberg stressed Europe and Canada were also stepping up with aid for Ukraine. He said their combined economic and military assistance to Kyiv was more than the U.S. had provided.
But he said U.S. report "remains vital".
"If President Putin wins in Ukraine, it will send a message to him but also to other authoritarian leaders that they get what they want when they use military force. It will make the world more dangerous (and) us more vulnerable," he added.
"Today it is Ukraine, tomorrow it can be in Taiwan. So Beijing, China is watching closely what's going on in Ukraine."
The U.S. Senate passed a $95.34 billion package of military aid for Ukraine and other U.S. allies on Tuesday. But it is unclear whether the Republican-controlled House of Representatives will even take up the proposal.
The approval of both houses of Congress is necessary before Democratic President Joe Biden can sign it into law.
Biden has been pushing for the package, which also includes security funding for Israel and Taiwan and humanitarian aid for Palestinians, for months, but has faced opposition from Republicans aligned with former President Donald Trump.
House Speaker Mike Johnson issued a statement before the Senate vote that faulted the bill for lacking conservative provisions to stem a record flow of migrants across the U.S.-Mexico border, suggesting he would not schedule a vote any time soon.
(Reporting by Andrew Gray and Johnny Cotton; editing by Charlotte Van Campenhout, Mark Heinrich and Angus MacSwan)
By Andrew Gray and Johnny Cotton
