The president has a broad mandate when it comes to international diplomacy. The Constitution gives him the authority to make treaties (with the advice and consent of the Senate) and recognize foreign governments. He can also enter into executive agreements with other heads of state.
Signing a Treaty
The president needs the consent of two-thirds of the Senate in order to enter into a foreign treaty. Some presidents have interpreted this to mean that the Senate should be consulted on all aspects of treaty negotiations, while others have viewed Senate approval as a rubber stamp.
Regardless of interpretation, the president is the one who drives the treaty process. He alone decides which treaties to pursue. He selects the negotiators, devises the negotiating strategy, and lobbies the Senate for approval. He can even reject a treaty that the Senate has approved if he doesn't like the changes made to it. A treaty is not officially recognized until the president signs it into law.
Although the president needs the Senate's consent to ratify a treaty, he does not need it to terminate one. The Constitution is silent on this issue, but the Supreme Court has held that the president alone should have the power to terminate treaties. In 2002, President George W. Bush terminated the Anti-Ballistic Missile (ABM) treaty with Russia, drawing criticism from some Democrats for not seeking Congressional input first.
An executive agreement is a pact between the United States and a foreign government that falls short of being a treaty, but binds the two countries to a mutual action such as arms reduction, trade agreements, military commitments, and territory annexation. An executive agreement is a powerful foreign policy tool because it does not require Senate approval and because it gives the president the flexibility to negotiate international agreements quickly and in secret — two important considerations when dealing with sensitive and timely matters.
The biggest difference between treaties and executive agreements is that treaties are binding on all future presidents, while executive agreements must be reauthorized by each succeeding administration. Executive agreements have grown increasingly popular over the past five decades. In total, there have been close to 10,000 executive agreements, compared to 1,500 treaties.
President John Tyler used an executive agreement to annex Texas in 1845. Tyler feared that the Senate would not approve annexation through a treaty, and he wanted to move quickly before another country laid claim to the Lone Star state. Following Tyler's precedent, President William McKinley annexed Hawaii as a territory through an executive agreement in 1898.
Although it's not an explicit power in the Constitution, the president also has the sole authority to recognize a foreign government. This power stems from the president's ability to receive and send ambassadors. Formal recognition of a foreign government is required before treaties, executive agreements, and other diplomatic actions can take place. The simple act of receiving a foreign diplomat is enough to officially recognize his or her government. In determining whether or not to recognize a particular foreign government, presidents typically take into account that country's record on human rights, its ability to govern its people, the moral character of the regime, and its willingness to abide by international law.
In some cases, presidents have used the recognition power to make a political statement. President Andrew Jackson recognized the independent country of Texas in 1836 because he knew it would provoke Mexico into a war with the United States. Harry Truman recognized the newly created state of Israel in 1946 as a way to support the fledgling country. In 1978, Jimmy Carter recognized the Palestinian authority in Israeli-occupied territories in an effort to jump-start the peace process. President Clinton severed relations with Afghanistan after the Taliban seized power, and President George W. Bush reinstated it after the provisional government of Hamid Karzai took control.