INDIANAPOLIS — President Donald Trump said Friday he is pulling the U.S. back from an international agreement on the arms trade, telling the National Rifle Association the treaty is “badly misguided.”

Trump made the announcement at the NRA’s annual convention, where he vowed to fight for gun rights and implored members of the nation’s largest pro-gun group to rally behind his re-election bid.

“It’s under assault,” he said of the constitutional right to bear arms. “But not while we’re here.”

The president told the group that he would be revoking the United States’ status as a signatory of the U.N. Arms Trade Treaty, which regulates the multibillion-dollar global arms trade in conventional weapons, from small arms to battle tanks, combat aircraft and warships.

President Barack Obama signed the pact, which has long been opposed by the NRA, in 2013. But it has never been ratified by U.S. lawmakers.

“Under my administration, we will never surrender American sovereignty to anyone,” Trump said, before signing a document on stage directing the Senate to halt the ratification process. “We will never allow foreign diplomats to trample on your Second Amendment freedom.”

His move against the treaty came as Trump sought to excite an organization that was pivotal to his victory in 2016. And it represents the latest in a series of withdrawals from international pacts and organizations joined by previous administrations, like the Paris climate accord and the Iran nuclear deal.

Gun activists had denounced the treaty when it was under negotiation as an infringement of civilian firearm ownership, despite the well-enshrined legal principle that says no treaty can override the Constitution or U.S. laws. The treaty is aimed at cracking down on illicit trading in small arms, thereby curbing violence in some of the most troubled corners of the world.

It was the first legally binding treaty to regulate the international trade in conventional arms and was overwhelmingly approved by the 193-member U.N. General Assembly in April 2013. It has been ratified by 101 countries — but key arms exporters including Russia and China and major importers such as India and Egypt have given no indication that they will sign it.

Advocates of tighter gun restrictions and those who had helped negotiate the treaty denounced Trump’s decision Friday.

Kris Brown, president of the Brady organization, said will “only embolden terrorists and other dangerous actors around the world.” And Rachel Stohl, managing director of the Stimson Center and a consultant to the treaty negotiations, said: “By turning its back on multilateral diplomacy yet again, the United States is disregarding global norms and allowing nefarious actors to trade weapons with impunity.”

At the United Nations, spokesman Stephane Dujarric called the treaty “a landmark achievement in the efforts to ensure responsibility in international arms transfers” and particularly important at a time of renewed interest in expanding weapons arsenals.