UNITED NATIONS (AP) - The U.N. General Assembly overwhelmingly approved the first international treaty regulating the multibillion-dollar global arms trade Tuesday, after a more than decade-long campaign to keep weapons from falling into the hands of terrorists, warlords, organized crime figures and human rights violators. Loud cheers erupted in the assembly chamber as the electronic board flashed the final vote: 154 in favor, 3 against and 23 abstentions. "This is a victory for the world's people," U.N. Secretary-General Ban Ki-moon said. The Arms Trade Treaty will make it more difficult for deadly weapons to be diverted into the illicit market. ... It will be a powerful new tool in our efforts to prevent grave human rights abuses or violations of international humanitarian law. The United States, the world's biggest arms exporter, voted yes. Iran, North Korea and Syria - all facing arms embargoes - cast the only no votes. They argued, among other things, that the agreement favors major arms suppliers like the U.S. over importers that need weapons for self-defense. Russia and China, which are also major arms exporters, abstained along with India and Indonesia, while nuclear-armed Pakistan voted in favor. Many Arab countries, including Egypt, Saudi Arabia, Sudan and Qatar, abstained, while Lebanon voted yes. Never before has there been a treaty regulating the global arms trade, which is estimated to be worth $60 billion today and which Amnesty International predicts will exceed $100 billion in the next four years. "Today's victory shows that ordinary people who care about protecting human rights can fight back to stop the gun lobby dead in its tracks, helping to save countless lives," said Frank Jannuzi, deputy executive director of Amnesty International USA. The voices of reason triumphed over skeptics, treaty opponents and dealers in death to establish a revolutionary treaty that constitutes a major step toward keeping assault rifles, rocket-propelled grenades and other weapons out of the hands of despots and warlords who use them to kill and maim civilians, recruit child soldiers and commit other serious abuses. What impact the treaty will actually have remains to be seen. It will take effect 90 days after 50 countries ratify it, and a lot will depend on which ones ratify and which ones don't, and how stringently it is implemented. As for its chances of being ratified by the U.S., the powerful National Rifle Association has vehemently opposed it, and it is likely to face stiff resistance from conservatives in the Senate, where it needs two-thirds to win ratification. Secretary of State John Kerry called it a "strong, effective and implementable" treaty and stressed that it applies only to international deals and "reaffirms the sovereign right of any state to regulate arms within its territory." The treaty prohibits countries that ratify it from exporting conventional weapons if they violate arms embargoes, or if they promote acts of genocide, crimes against humanity or war crimes, or if they could be used in attacks against civilians or schools and hospitals. Countries must also evaluate whether the weapons would be used by terrorists or organized crime or would undermine peace and security. They must take measures to prevent the weapons from being diverted to the black market. The treaty covers battle tanks, armored combat vehicles, large-caliber artillery systems, combat aircraft, attack helicopters, warships, missiles and missile launchers, and small arms and light weapons. Enforcement is left up to the nations that ratify it. The pact requires these countries to assist each other in investigating and prosecuting violations. "The treaty is a noble gesture that may over time acquire the kind of precedence or enforcement that would give it meaning," said Anthony Cordesman, an analyst at the Center for Strategic and International Studies in Washington. At this point it is more a declaration of principles - and the arms trade is an area where many people don't have principles. Supporters of the treaty agreed that it is just a first step and that it must be followed by a campaign for implementation. "The hard work starts now," said Juan Manuel Gomez Robledo, Mexico's vice minister for multilateral affairs. Australian Ambassador Peter Woolcott, who chaired the negotiations, said the U.S. "played a hugely constructive role" in pushing the treaty through the United Nations. "Obviously, as the world's largest exporter, it would be unfortunate for the Arms Trade Treaty if the U.S. didn't sign it, but obviously it's a sovereign decision for them," he said. Hopes for adoption of the treaty by consensus instead of a vote were dashed last July when the U.S. said it needed more time to consider it. At the end of the final negotiating conference last week, Iran, North Korea and Syria blocked another attempt at consensus. Over those countries' objections, the treaty's supporters decided to put it to a vote in the General Assembly. Associated Press writers Ron DePasquale at the United Nations and Desmond Butler in Washington contributed to this report.