Why can't the U. S. A. and Nato send poor Ukraine military donating them some jet planes, at least old jets from the 80's and 90's to help them out?

Ukraine is begging for help with jets to defend their skies from the bombings.
Why cant the U. S. A. and Nato send poor Ukraine military donating them some jet planes, at least old jets from the 80s and 90s to help them out?
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For all you saying the U. S. does need to get involved as that will escalate things yet Biden said that if Russia uses bio weapons on Ukraine then the U. S. will get involved along with Nato.

www.cnbc.com/.../...cal-or-biological-weapons.html
Updates
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*doesn't
Why can't the U. S. A. and Nato send poor Ukraine military donating them some jet planes, at least old jets from the 80's and 90's to help them out?
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