Donald Trump will call for a new ideological test for admission to the United States, vetting applicants on their stance on issues like religious freedom, gender equality and gay rights.
The policy would represent a significant shift in how the US manages entry into the country.
In a speech in swing state Ohio today, Trump will also call for "foreign policy realism" and an end to nation-building if elected president.
And he'll argue that the United States needs to work with anyone who shares the mission of destroying the Islamic State group and other extremist organisations, regardless of other disagreements.
"Mr Trump's speech will explain that while we can't choose our friends, we must always recognise our enemies," Trump senior policy adviser Stephen Miller said.
The Republican nominee's foreign policy address comes during a rocky stretch for his campaign. He's struggled to stay on message and has consistently overshadowed his policy rollouts, including an economic speech last week, with provocative statements, including falsely declaring that President Barack Obama was the "founder" of the Islamic State.
Democrat Hillary Clinton has spent the summer hammering Trump as unfit to serve as commander in chief. She's been bolstered by a steady stream of Republican national security experts who argue the billionaire businessman lacks the temperament and knowledge of world affairs to be president.
Clinton is focusing on domestic themes today as she campaigns in Pennsylvania with Vice President Joe Biden. Trump is expected to spend significant time in his speech going after Obama and Clinton, the former secretary of state, blaming them for policies he argues allowed the Islamic State group to spread.
Trump is expected to say that any country that wants to work with the US to defeat "radical Islamic terrorism" will be a US ally, though aides did not specify which countries that position refers to.
He'll also call for declaring in explicit terms that, like during the Cold War, the US is in an ideological conflict with radical Islam.
Obama, Clinton and top US officials have warned against using that kind of language to describe the conflict, arguing that it plays into militants' hands.
"Mr Trump will outline his vision for defeating radical Islamic terrorism, and explain how the policies of Obama-Clinton are responsible for the rise of ISIS and the spread of barbarism that has taken the lives of so many," Miller said Sunday in an email, using an alternative acronym for the Islamic State group.
Under Trump's new immigration policy, the government would use questionnaires, social media, interviews with friends and family or other means to determine if applicants support American values like tolerance and pluralism.
The US would stop issuing visas in any case where it cannot perform adequate screenings.
It is unclear how US officials would assess the veracity of responses to the questionnaires or how much manpower it would require to complete such arduous vetting.
The campaign has yet to say whether additional screenings would apply to the millions of tourists who spend billions of dollars visiting the United States each year.
It will be the latest version of a policy that began with Trump's unprecedented call to temporarily bar foreign Muslims from entering the country, a religious test that was criticised across party lines as un-American.
Trump said he will keep that the radical Islamic
terrorists "the hell out" of the country.
"At the same time, we're going to take care of our military and we're going to take care of our great, great, great veterans," he said.
"We're going to stand up to China, we're going to stop their currency manipulation and product dumping, which is killing us. And they don't follow the rules and, if they don't, we're going to institute tariffs. When they send something into our country - and, believe me, they're going to obey our rules so quickly, you have no idea. And we'll end up with a better relationship with China than we do now," he said.
Referring to South China Sea, Trump said the Chinese were building a massive fortress against everything.
"A massive fortress in the South China Sea. Yet they're ripping us off. Now, if they're going to rip us off, you wouldn't think they'd be building fortresses. They have no respect for our President - which I can understand that - they have no respect for Obama, they have no respect for our country, and they're getting away with murder," he said.
