President Obama was in London on Friday, warning the British people against leaving the European Union. He has already been sharply criticized by British members of Parliament, including London Mayor Boris Johnson. And with good reason: Obama is sending the wrong message.

His intervention is proving both controversial and unpopular, a demonstration of how out of touch he is with public sentiment in the United Kingdom, at a time when there are mounting concerns with rising immigration from Europe and the growing Islamist terror threat on the continent.

America has nothing to gain from Great Britain staying in the EU. If the British vote for Brexit in the June 23 referendum, the U.S. should welcome their decision.

The EU has evolved into a decaying, overregulated, bureaucratic and fundamentally undemocratic entity. It is a monument to supranationalism and big government, increasingly trampling upon the power of nation states. Britain, like the 27 other members of the European Union, is no longer a sovereign nation and does not possess the power to fully control its own borders.

EU regulations have a huge impact on British law, and British courts can be overruled by the European Court of Justice in Luxembourg. The European Commission, the executive body of the EU, actively intervenes in the internal affairs of European countries and acts like a power on the world stage, running its own network of embassies across the globe.

It is in America’s interests to have a British ally that is able to act independently and robustly, without being constrained by Brussels. Brexit would reinvigorate the U.S.-U.K. special relationship, and it would boost trade and investment between the two nations. Freed from the shackles of the EU, Britain would be able to sign a free-trade agreement with the United States, advancing economic freedom on both sides of the Atlantic.

The U.S. has nothing to fear but plenty to gain from Brexit. We should applaud the British if they walk away from the failing European project.

- Nile Gardiner is the director of the Margaret Thatcher Center for Freedom at  Foundation.