There are many reasons 

1️⃣ U.S. does not recognize Nicolás Maduro as the legitimate president
The U.S. and several Western countries say that Maduro’s elections were not free or fair, so they support opposition leader Juan Guaidó (earlier) or other democratic factions.
This political dispute is the root of most tensions.

2️⃣ Venezuela’s close ties with U.S. rivals (Russia, Iran, China)
Venezuela has strong partnerships with:

• Russia (military, intelligence, energy)
• Iran (oil shipments, fuel, drones, financial networks)
• China (loans, infrastructure, tech surveillance systems)
• The U.S. sees this as a strategic threat in its own hemisphere.

3️⃣ Oil and sanctions
Venezuela has some of the largest oil reserves in the world. The U.S. has imposed heavy sanctions on Venezuela’s oil industry to pressure Maduro. Because of sanctions, Venezuela started:

• secretly exporting oil
• using “dark fleet” ships
• partnering with Iran to move crude
• This led the U.S. to seize tankers, as seen in the recent incident off Venezuela’s coast.

4️⃣ Human rights and democratic concerns
The U.S. accuses Venezuela of:

• suppressing the opposition
• arresting activists
• manipulating elections
• violating human rights
• running the economy into collapse
• Washington uses sanctions to force political reforms.

5️⃣ Drug trafficking accusations
The U.S. has long alleged that officials in Maduro’s government are involved in drug trafficking networks.
This has led to:

• U.S. indictments
• Rewards for arrest of top officials
• Military surveillance missions around the Caribbean

6️⃣ Migration crisis affecting the U.S.
Millions of Venezuelans have left the country due to economic collapse.
Many travel to the U.S.–Mexico border, increasing political pressure in the U.S.
Washington blames Maduro’s governance for this crisis.