Our robot overlords think it's congress duty, but the president has the authority as well.

In the United States, the power to set tariffs—taxes on imported goods—primarily lies with the legislative branch of government. Specifically, the U.S. Congress has the constitutional authority to regulate foreign commerce, which includes setting tariffs.
However, in practice, Congress often delegates some of this power to the executive branch (the President and related agencies like the Office of the U.S. Trade Representative) through trade laws that allow the president to adjust tariffs under certain circumstances (for example, in response to unfair trade practices or national security concerns).
So, while Congress sets the rules and framework for tariffs, the president can sometimes adjust them within those guidelines.