The approval of the Senate
The Executive branch has the authority to negotiate and enter into treaties with foreign countries. However, the Senate must ratify the treaty by a two-thirds majority before it becomes legally binding.
The Executive branch decides is a treaty is unconstitutional
States cannot declare war or enter into treaties with other countries, as those powers are reserved for the federal government. Additionally, states cannot coin their own money or infringe on the rights protected by the U.S. Constitution.
It isn’t a treaty nor valid.
In the United States, the Executive Branch (President) will negotiate a treaty, and it must be consented to by the Senate with a 2/3 affirmative vote. After this, the President can ratify the treaty.
The president can make executive agreements with foreign heads of state that do not carry the status of treaty and so avoid Senate confirmation.
In the United States, the Executive branch provides the process for signing and approving treaties with foreign entities (generally the responsibility of the President).However, the Legislative branch (specifically the Senate) is responsible for ratifying any treaty signed by the President. A two-thirds majority in the Senate must approve the treaty in question for it to be officially ratified.
two-thirds
The Executive Branch (the President/State Department)
In the US, the power of the executive branch of government has been growing. This impacts both foreign and domestic affairs. For example, the US president signed a executive order to create a set of policies that allows Iran to make certain limited progress in nuclear physics in return for the unfreezing of assets mandated by violating UN resolutions. The US Congress opposed this so-called treaty but did not have enough votes to overturn the treaty with Iran. In years past, a US president seldom made foreign treaties or agreements without the support of the US Congress, specifically the US Senate. Executive power may be reaching a point of critical mass however.
The executive branch (the president) has the power to with the consent and advice of the Senate.
In the United States the executive branch appointed people to negotiate treaties with Native Americans. The treaty was not in effected unless it was in line with the advice and consent of the US Senate. Certainly there may have been minor details of a treaty the the executive branch was allowed discretion.