Legislative
The Senate must approve treaties and presidential appointments.
legislative branch
The Legislative Branch
The Secretary of State typically negotiates treaties. The Senate must ratify any treaty before it become binding.
The executive (the President) negotiates the terms of treaties. The Senate must approve them as a condition of their ratification.
The Legislative branch but more specifically the Senate. The president proposes but the Senate must approve by 2/3 of the vote.
The Senate ratifies treaties entered into by the executive branch of government.
In the US, only the Federal Government can do this; states cannot do this individually.
The Senate has the responsibility of approving treaties.
The legislative branch, also known as Congress in teh United States of America
The executive branch negotiates treaties. The Senate must approve those treaties. The answer can be found in Article II Section 2 of the US Constitution. It reads: "He shall have Power, by and with the Advice and Consent of the Senate, to make treaties, provided two thirds of the Senators present concur" (He is referring to the President.)
They must meet with the other countries, work out the details and agree to it, finalize the treaty into a bill of sorts, and the Senate must confirm it with a vote of 2/3. Pretty cut-and-dry.