There are many things the US government could have done to topple the Maduro regime short of starting a war:
Here's a few, off the top of my head:
1. Decriminalize all drugs. This would cause the black market in drugs to collapse, and cut off a major source of funding for many dictatorial regimes, including Venezuela.
2. Offer green cards to all STEM degree holders in Venezuela. If most of their smart/competent people (engineers, scientists, and doctors ) flee, it would enrich the US and deprive them of the ability to fight insurgent forces. Those people would also send millions in remittances to the opposition.
3. Offer green cards to families of prominent opposition leaders in Venezuela. This would allow them to fight without fear that their children/parents would be killed/imprisoned.
4. Offer social policy bonds that pay out when the Maduro regime steps down and is replaced by the duly elected leaders. Give the bonds to the current leaders so that they're financially incentivized to step down.
5. Offer "Club Fed" style imprisonment/asylum to Maduro and his lackeys so that they don't fear that they will be killed when the new regime takes power. This has been done many times in the past:
* In 1986, Ferdinand Marcos of the Philippines was provided safe passage and a secure exile in Hawaii by the United States government following the People Power Revolution.
* Similarly, Idi Amin of Uganda was granted sanctuary in Saudi Arabia in 1979, where he lived for decades under a government-provided pension and protection from extradition.
* Charles Taylor of Liberia, Bashar al-Assad of Syria, Yahya Jammeh of the Gambia also took advantage of asylum offers.
