President Donald Trump followed through on one of his signature campaign promises and announced Thursday that the United States will withdraw from the Paris Agreement on climate change.

The Paris Agreement is an international accord intended to reduce worldwide greenhouse gas (GHG) emissions and mitigate the effects of climate change. Nearly 200 countries signed the Agreement, which took effect in November 2016. The Agreement is not a binding treaty. Instead, the signatories agreed to set voluntary, individualized carbon emission targets. The U.S. target was to reduce GHG emissions by 26–28% below 2005 levels by 2025.

The President’s announcement does not mean the United States leaves the Agreement immediately. Leaving the Agreement is expected to take up to four years, as the Agreement sets a three-year moratorium on withdrawals, and withdrawal takes one year to complete. This process may allow time for the United States to reengage in further negotiations. The United States also remains a party to the U.N. Framework Convention on Climate Change, a treaty ratified by the Senate and signed by President George H.W. Bush.

Withdrawal fits with the new Administration’s agenda to promote domestic fossil fuel development. By Executive Orders, President Trump has sought to promote U.S. economic growth by directing federal agencies to reconsider federal rules that have restricted the development and use of domestic energy resources, particularly the development and use of fossil fuels that produce GHG emissions. Withdrawal from the Agreement fits firmly within those goals, including the President’s direction to EPA to review the agency’s Clean Power Plan, one of the previous administration’s stated methods for achieving the U.S. targets. Exiting the Agreement will give the EPA more flexibility in implementing the President’s orders.

The responses of other governments bear close watching. In the lead up to the President’s decision, much has been said about how other parties to the Agreement may react to a U.S. withdrawal. For example, the world’s largest source of GHG emissions, China, came to the Agreement with the United States on board. Without U.S. participation, China could decide to take on a larger leadership role or, with other large sources of GHG emissions, such as India, could instead choose to join the United States in withdrawal. Further, there has been speculation that some signatories may attempt to use trade (such as a tariff on the carbon content of exports from the United States) to take a tougher stance with the United States. These actions could result in additional costs for U.S. businesses.