"The United Nations will soon receive a formal notice that America is rejecting this treaty," Trump said in a speech at the NRA convention in Indianapolis. The treaty was not supported by the NRA.
"We will never allow foreign bureaucrats to trample on your Second Amendment," Trump said to applause and acknowledged the "happy faces from the NRA over there."
Trump signed a document before the crowd, which he said was a "message asking the Senate to discontinue the treaty ratification process and return the now-rejected treaty right back to me in the Oval Office, where I will dispose of it." The move, however, is mostly symbolic. The Obama administration submitted the treaty to the Senate, but it was never ratified after facing opposition. Senate Majority Leader Mitch McConnell has not signaled how lawmakers will move forward with the president's request.
Immediately, gun control advocates spoke out against the president's decision to back away from the treaty, which seeks to make it more difficult to sell weapons to countries that are under arms embargoes, often because of conflict.
"The Arms Trade Treaty is designed to keep guns out of war-stricken countries and prevent dangerous situations from descending even further into chaos. It is a treaty supported by our allies, but in opposing it, the president instead chose to stand with countries such as North Korea and Syria," said Kris Brown, the president of Brady, an organization aimed at preventing gun violence.
As he took the stage, it appeared that a phone was thrown at but did not strike the president. ABC News has reached out to the Secret Service.
During his speech, Trump jumped from defending Second Amendment rights to building a wall to touting economic numbers.
The president argued that while Democrats advocate for undocumented immigrants, they want to "disarm law-abiding citizens."
"Democrats want to disarm law-abiding Americans while allowing criminal aliens to operate with impunity. But that will never happen as long as I'm your president. Not even close," the president said.
Trump also claimed he had successfully fought back against the corruption "at the highest levels" in Washington in his speech at the NRA's annual convention in Indiana, held one week after special counsel Robert Mueller’s redacted report was released to the public.
"All was taking place at the highest levels in Washington, D.C. You’ve been watching, you've been seeing. You've been looking at things that you wouldn't have believed possible in our country. Corruption at the highest level a disgrace. Spying, surveillance. Trying for an overthrow. And we caught them. We caught them," he said.
Earlier, Vice President Mike Pence took a swipe at newly announced Democratic presidential candidate and former Vice President Joe Biden on Friday saying that the nation is not in a battle for the "soul of America."
"I heard the other day that another vice president actually said we are in a ‘battle for the soul of our nation,’ and for once I agree with him. But not for the reason he thinks. we are in a battle," Pence said. "We are in a battle for the soul of America but it is a battle between liberty and tyranny."
Pence went on to criticize Democratic proposals such as the Green New Deal, a wide-reaching proposal that would address climate change co-sponsored by Rep. Alexandria Ocasio-Cortez, D-N.Y., and Medicare for all which 2020 presidential candidate Sen. Bernie Sanders reintroduced as his signature health care legislation earlier this month.
Pence depicted the proposals as socialist efforts that threaten liberty and declared to a standing ovation that "America will never be a socialist country."
"We are in a battle for the soul of America but it is a battle between liberty and tyranny," said Pence who spoke ahead of Trump. "Mr. President has said before it is a battle between Independence and government control and ultimately it’s a battle between freedom and socialism. Under the guise of the green new deal and Medicare for all, the same Democrats who want to take away your freedom openly advocate a failed economic system that has robbed the liberty and impoverished millions of people around the world."
Pence ended by insisting that the best way to safeguard such freedoms is by re-electing Trump to the White House "for four more years."
The president and the vice president’s comments hit on a range of issues far beyond the Second Amendment, further emphasizing the NRA’s push to be a home for the broader conservative conversation.
One example of that expansion is NRA TV, where members can find shows on gun policy alongside criticism of the Green New Deal and Ocasio-Cortez.
There's one thing on which both gun enthusiasts and gun control activists agree: The NRA isn't the same organization it was decades ago.
The NRA spent $30.3 million to support Trump's campaign in 2016, according to Open Secrets, and doubled down on NRA-sponsored advertising in key states where the president claimed victory.
But in the past year alone, the NRA has faced staggering opposition. After the Feb. 14, 2018, deadly mass shooting at Marjory Stoneman Douglas High School, students and supporters from Parkland, Florida, were among those asking other companies to sever their ties with the NRA.
In the 2018 midterm elections, the NRA was outspent by gun control activists, as Democratic candidates fed up with mass shootings campaigned on the issue. Gun control advocates Lucy McBath in Georgia and Jason Crow in Colorado were among a group of Democrats who beat out Republicans for congressional seats.
For many voters, the debate over firearms likely will remain a key issue in 2020, with voters on both sides gearing up to back candidates on both sides of the issue. Ahead of the 2018 midterms, 60% of voters listed gun policy as "very important" among voting choices, according to the survey by the Kaiser Family Foundation.
In Greenfield, Indiana, Mark Highsmith said he believes firearms are woven into the fabric of the state. He owns a gun shop and told ABC News the NRA remains strong in parts of the country because it's the only organization on the front lines of gun advocacy.
"They're really the only lobbying group for the shooting public," Highsmith told ABC News ahead of Trump's speech. But, he added, "I think they need to try and rationalize how they spend their money and try to be more steadfast in the way they do business. I'd like to see them be more supportive of places like me -- how are they helping the average member."
Highsmith is in a unique position as a gun shop owner. While he personally supports Trump, it hurts his business.
"When Trump got in, our business slowed quite a bit -- anytime you got a Democrat House and Senate, I really think it makes people alarmed," he said.
Some gun enthusiasts have labeled that decline in firearm sales the "Trump Slump." The president's 2016 campaign, heavily backed by the NRA, helped reassure gun owners, so they bought fewer firearms.
That said, the NRA and Trump don't always agree -- the president has called for raising the purchasing age to 21 from 18 despite fierce opposition from the group.
"The NRA is opposed to it," Trump said in February 2018, "and I'm a fan of the NRA. No bigger fan. I'm a big fan of the NRA. These are great people. Great patriots. They love our country, but that doesn't mean we have to agree on everything."
The NRA also disagreed with the Trump administration's ban on bump stocks following a mass shooting at a Las Vegas music festival in October 2017 that killed 58 people. That shooter used a bump stock, a device that allows a rifle automatic or semiautomatic firing capability.
As the president and vice president headed to Indianapolis for the convention, gun control activists planned to respond with force.
Everytown for Gun Safety Support Fund launched a campaign investing $100,000 in ads, which will be seen in Indianapolis during this week's annual NRA convention.
"The NRA isn't really a gun rights group anymore -- it's a troubled business committed to enriching its executives and gun manufacturers," said John Feinblatt, president of Everytown for Gun Safety.
Moms Demand Action will hold a counter-event this weekend as the NRA convention takes place.
"We will work against candidates who buy into the NRA's distorted vision of gun everywhere, all the time, for everybody," Stephanie Mannon Grabow, a volunteer with Moms Demand Action, told ABC News. "We know we can protect the Second Amendment and protect our communities. The NRA is coming here to put on a big show, but we know behind the curtain, they are struggling."