In order for a treaty to be ratified (once the President has signed it), it requires two-thirds of the US Senate.
Specifically, Article 2, Section 2, Clause 2 of the US Constitution states:
"[The President] shall have Power, by and with the Advice and Consent of the Senate, to make Treaties, provided two thirds of the Senators present concur;"
It depends on the constitution, if any, and the legislation of the country in question.
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The Legislative Branch can ratify treaties; The Senate approves Presidential Appointments
ratify
The Congress
Congress can
it is the supreme authority of senate to ratify treaties with foreign nations by a majority of vote.
The president can make treaties, but Congress must ratify them.
us senate
The U. S. Senate must ratify all treaties.
The legislative branch is responsible for the approval and ratification of treaties.
Diplomats negotiate treaties, government officials sign them, and national legislatures ratify them.