Here’s the scenario. You’re the Pres, shaken awake from your afternoon nap in the Oval Office. After a knock on the door the Secretary of Defense leads in several odd looking but physically unimposing creatures.
You begin to wonder if someone has been spiking your banana daiquiris when one of them starts to speak. They explain that they represent a peaceful alliance of spacefaring species. They have come to Earth in desperation - in the last few years their colonies have been attacked by an insectoid race that attacks any spacefaring species and rejects any attempts at negotiation or surrender.
Their alliance has not known war for millennia. Violence of any kind is unknown. They are losing the fight, badly. Having observed Earth for several centuries they see that humans are warriors - with our help they can turn the tide. The weapons, martial knowledge and killer instinct of humans are all they’ll need - they will drop our troops on worlds under attack and share all the intelligence on the conflict they possess.
In return for our service, they will share their technology. They estimate it will advance our development in all areas by at least 300 to 400 years. The fighting they believe will take about a year or two until total victory, and inflict casualties on us about equal to the Normandy campaign in WWII - about 40,000 killed, about 150,000 wounded. As they haven’t a clue how to wage war they will give humans complete authority over the fighting.
If you reject their pleas they will leave Earth and never bother us again, although they anticipate total defeat in 2-3 years. Asked why they haven’t contacted us before, they reply that they were afraid they would simply be gunned down. What do you tell this alliance of space hippies?