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On January 7, 2026, President Donald Trump signed an executive order instructing federal agencies to cease participation in and funding of 66 international organizations and treaties, including the main UN climate treaty (called the UNFCCC) and the Intergovernmental Panel on Climate Change. The mechanics of withdrawal unfold over months and years, governed by procedural requirements that no president can simply override with a signature.
The UNFCCC contains a specific rule that says you have to notify the UN in writing, followed by a mandatory one-year waiting period. That year cannot be shortened or waived. Even if Trump wants the U.S. out now, the treaty’s written rules prevent it. The U.S. remains fully bound by the treaty’s rules for twelve months after formal notification reaches the UN’s treaty office.
This same problem applies to all 66 organizations. Some have 30-day notice periods. Others require three years. A few have no withdrawal clause at all, creating legal questions about whether unilateral exit is possible under international law. The Trump administration’s withdrawal will unfold on a staggered timeline, with some organizations losing U.S. participation within weeks while others keep it for years.
The Unsolved Constitutional Question
The Constitution specifies exactly how treaties get made: the President negotiates, the Senate officially approves it with a two-thirds vote, and the treaty becomes the supreme law of the land. The Constitution does not specify how treaties get unmade.
This silence has created a constitutional standoff that’s persisted for decades. One camp argues that if Senate approval is required to enter a treaty, Senate approval should be required to exit. The other contends that the President’s basic authority over foreign policy includes the authority to withdraw from agreements, similar to recalling ambassadors or ending diplomatic relations.
The Supreme Court had a chance to settle this in 1979 with Goldwater v. Carter, when Senator Barry Goldwater sued President Carter over his withdrawal from a mutual defense treaty with Taiwan. The Court avoided deciding, saying this was a dispute between branches of government, not a court matter. The constitutional question remains unsettled.
Presidents have proceeded on the assumption they can withdraw unilaterally. Trump withdrew from the Paris Agreement in his first term without asking the Senate. Biden reversed that withdrawal, also without asking the Senate. Neither action was challenged in court.
The current withdrawal differs because it targets Senate-ratified treaties like the UNFCCC. If someone with the legal right to sue challenges Trump’s authority to withdraw from it without Senate approval, we might finally get a definitive answer to a question that’s been hanging since 1979.
The Withdrawal Process: Step-by-Step
The executive order Trump signed on January 7 did not withdraw the U.S. from anything. It authorized federal agencies to begin the withdrawal process—a process governed by each treaty’s specific language, international institutional procedures, and State Department regulations.
Step one: Determine the rules. The State Department’s Legal Adviser’s office must examine each of the 66 organizations to determine: Does the founding document say how to leave? Who do we notify? What timeline applies? What bills do we owe?
For the UNFCCC, those answers are clear. A specific rule spells out the procedure: Written notification goes to the UN Secretary-General. One year after the Depositary receives that notification, withdrawal becomes effective. During that year, the U.S. remains a full party with all rights and obligations.
Other organizations are messier. Some lack withdrawal clauses entirely. The International Law Commission isn’t really an organization you join—it’s a UN group of legal experts. U.S. withdrawal probably means American legal experts stop getting nominated for positions, quite different from formal treaty withdrawal.
Step two: Write the official letter. This becomes a binding legal document. It must clearly state the U.S. is leaving, cite the treaty article authorizing withdrawal, and specify the proposed effective date. Once sent, it cannot be taken back unless everyone agrees.
Step three: Send the letter to the right place. For most UN treaties, that’s the UN’s main office. The date of transmission (or receipt, depending on the treaty’s language) triggers the notice period countdown. Legal scholars debate whether the one-year clock starts when the U.S. sends the letter or when the UN receives it, which could change when the U.S. leaves by weeks or months.
Step four: The UN verifies and notifies other countries. The UN must confirm the letter comes from someone with the power to speak for the government and check that procedures were followed. The UN cannot refuse because it dislikes the choice, but it can ensure the rules were followed. Once verified, the UN tells all the other countries. For UNFCCC, that means informing 196 countries and regional groups that the U.S. has notified its intent to withdraw and specifying when withdrawal becomes effective.
The Waiting Period Problem
Trump ordered agencies to stop participating in and paying for those organizations, but only if the law allows it. During the waiting period, the U.S. is still required to follow the treaty’s rules. The President cannot order agencies to break the rules while the U.S. is still officially part of the treaty.
The UNFCCC holds yearly meetings where member countries negotiate climate policy. If “ceasing participation” means the U.S. won’t send people to the next yearly meeting, the treaty probably requires countries to participate. If the U.S. doesn’t show up while still officially part of the treaty, it breaks the rules—which gives other countries a reason to say the withdrawal isn’t legal.
This happened when Trump withdrew from the Paris Agreement in his first presidency. He ordered the U.S. to stop funding climate programs and stopped participating in Paris meetings even though the one-year waiting period wasn’t over. Other countries complained but didn’t sue. It’s unclear if they could have won a case against the withdrawal in an international court.
This withdrawal is more serious. Catholic groups and climate leaders have condemned the U.S. exit from what they call bedrock climate frameworks. If the U.S. stops participating before the withdrawal is official, those groups or other countries might challenge whether the U.S. followed the rules.
Why Rejoining Is Harder Than Leaving
The Paris Agreement shows the difficulty of reversal. Trump announced withdrawal in June 2017. The Paris Agreement requires a three-year waiting period from when it started (April 22, 2015) plus one more year after notification. Trump couldn’t officially notify until November 2019, and the withdrawal didn’t take effect until November 4, 2020—the day after the presidential election.
When Biden took office in January 2021, he moved to reverse the withdrawal through executive action. Because the U.S. had already officially completed its withdrawal from the Paris Agreement, Biden had to formally rejoin as if the U.S. were entering anew. Biden signed the instrument of acceptance on January 20, 2021, his first day in office, and the U.S. formally rejoined the Paris Agreement on February 19, 2021, when the acceptance took effect thirty days after submission to the UN.
The Biden administration argued that the 1992 Senate approval of the main climate treaty automatically allowed participation in newer agreements like Paris, so the President could rejoin without Senate approval. Legal experts disagree about this argument and a court might reject it.
That legal argument won’t work for the main climate treaty. If the U.S. leaves the UNFCCC, rejoining would require either new Senate approval or a weak legal argument.
Getting Senate approval again is nearly impossible. The Constitution requires two-thirds of Senators to approve—67 out of 100. In 1997, the Senate passed a resolution 95-0 saying the U.S. shouldn’t join any climate deal that requires emissions cuts unless developing countries do the same. That resolution still influences how the Senate votes on climate deals today.
Once the U.S. leaves the main climate treaty, a future president would either need Senate approval (nearly impossible) or use a weak legal argument. Either option is risky.
Different Organizations, Different Timelines
The 66 organizations fall into three categories with different procedural requirements.
Treaties the Senate approved, like the UNFCCC, must follow whatever leaving procedures the treaty specifies. These usually require long waiting periods—one year for UNFCCC, three years for others.
Agreements the President made without Senate approval are simpler. The President created them alone and can end them alone. But even these agreements usually have their own rules about how to leave and waiting periods.
For memberships without formal treaties, leaving might be as simple as telling the organization’s leadership. Some memberships are written into the organization’s rules, which specify how to leave.
The Green Climate Fund shows how complicated this gets. It’s not a treaty but an organization set up to manage money for climate help to poor countries. The Green Climate Fund has its own rules about how countries join, leave, and stop participating, which don’t follow the UNFCCC’s one-year waiting period.
ICCROM, an international organization for preserving cultural property, is another example. It’s an organization created by UNESCO with its own rules. ICCROM’s leaders said U.S. withdrawal could hurt the organization, noting the U.S. has been important for money and expertise since 1971. Leaving follows whatever rules ICCROM’s founding document specifies.
The Trump administration will leave different organizations at different times. Some might see the U.S. leave within weeks. Others will take months or years to complete.
Historical Precedent: The UNESCO Pattern
The U.S. leaving UNESCO shows what happens when you leave and come back. The U.S. left in 1984 during Reagan’s presidency because it said UNESCO was biased against America and Israel. The U.S. rejoined in 2002. Trump withdrew again in 2017 citing similar concerns. Biden rejoined UNESCO on July 10, 2023.
Each time the U.S. left and came back, there were problems. The U.S. owed money for the time it was gone. The U.S. lost trust with other countries. Other countries stopped trusting the U.S. because it kept leaving and coming back.
The U.S. withdrawing its signature from the Rome Statute in 2002 is another example. The Rome Statute created the International Criminal Court, which prosecutes war crimes. Clinton signed it but never asked the Senate to approve it. When Bush took office, he officially told the UN the U.S. was taking back its signature. This is different from leaving a treaty the Senate approved. A treaty you didn’t get approved doesn’t bind the U.S., so taking back your signature doesn’t need a waiting period or Senate approval.
The UN’s Role as Treaty Record-Keeper
The UN Secretary-General serves as the official record-keeper for hundreds of international treaties. When a country submits a withdrawal letter, the UN must check that it comes from someone with the power to speak for the government, usually the Foreign Minister. It must verify that the person had the power to do this and that the treaty’s rules were followed. The letter must be clear enough to count legally.
The UN cannot refuse to process the letter because it disagrees with the choice. It cannot refuse because it dislikes the decision. The UN’s job is to check that the rules were followed, not to judge whether the decision is right.
Once verified, the UN tells all the other countries. For UNFCCC, that means telling 196 countries and regional groups. The UN also keeps detailed records of every withdrawal letter, including when it was sent and received. These records become official and any country can examine them. They can also be used as evidence if countries argue about whether the rules were followed.
Timeline of Events
January 7, 2026: Trump signs the order. This lets agencies start the process but doesn’t officially tell the UN anything.
January 7-31, 2026: The State Department prepares official withdrawal letters for each organization, figures out who to notify, and checks the waiting periods.
January 2026 onward: Official letters start going to the UN.
Once the UN gets the UNFCCC letter: The one-year waiting period starts. During this time, the U.S. remains fully part of the treaty.
Other organizations: Different waiting periods mean the U.S. leaves at different times.
Ongoing: If someone sues saying the President cannot leave Senate-approved treaties or didn’t follow the rules, courts could get involved.
Long-Term Implications
How hard it is to leave treaties shows something important about how countries keep promises. Treaties aren’t political statements that can be undone with a signature. They’re legal documents with specific rules, waiting periods, and requirements that work no matter what one official wants.
A future president wanting to rejoin the UNFCCC would either need Senate approval (nearly impossible) or use a weak legal argument. The rules about leaving might make it impossible to come back, a problem that lasts long after this administration is gone.
When countries leave treaties, other countries become much less willing to make new deals with them. This causes long-term damage that goes beyond any one disagreement.
The unsolved constitutional question about whether the President can leave Senate-approved treaties is at the heart of this. The Trump administration assumes the President can do this, but if someone sues and a court says the President cannot, the whole withdrawal could be canceled.
Saying you’re leaving is quick. Leaving according to the rules takes much longer. The gap between saying you’re leaving and leaving is measured in months and years, not days.
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