Since Donald Trump called for temporarily banning Muslims from entering the U.S., he has tried to expand, narrow or otherwise redefine the polarizing plan that helped win him the GOP primary.

On Monday, he added a phrase to his policy lexicon: "extreme vetting," in which the U.S. would screen out those who don't "share our values and respect our people."

The newest addition to Trump's immigration policy came during a major speech on national security in Youngstown, Ohio, that featured an unusually subdued Trump reading uneasily at times from a teleprompter and repeating several false claims, including his assertion that he was early to oppose the Iraq invasion and the unsubstantiated pronouncement that the neighbor of the San Bernardino, Calif., shooters saw bombs in their apartment before the attacks.

The speech followed days of criticism over Trump's insistence that President Obama and Hillary Clinton founded ISIL. Those comments, and other unscripted and unforced controversies, have helped distract from Trump's core economic and anti-terrorism messages and led Republicans to once again urge him to curtail his improvisational style of campaigning.

Trump did not explicitly back down from his December proposal, still on his campaign website, for "a total and complete shutdown of Muslims entering the United States until our country's representatives can figure out what is going on."

He did not mention it, instead calling on the State Department and the Department of Homeland Security "to identify a list of regions where adequate screening cannot take place," where visas would be temporarily halted. Trump spent more of his speech defining what he said was a new ideological test for those entering the U.S., comparing his plan to Cold War-era screening.

"We should only admit into this country those who share our values and respect our people," he said. "In addition to screening out all members or sympathizers of terrorist groups, we must also screen out any who have hostile attitudes towards our country or its principles — or who believe that [sharia] law should supplant American law. Those who do not believe in our Constitution, or who support bigotry and hatred, will not be admitted."

Trump mostly delivered broad outlines for his ideas on fighting terrorism, many of which he has mentioned before, rather than specific policy proposals. Some of his ideas, like relying on more human intelligence to target terrorists in addition to drone strikes, echo Obama administration policy. The message from Trump, however, was that Obama and Clinton have tiptoed around the threat because they are unwilling to use the phrase "radical Islamic terrorism" and are too afraid of offending those who would do harm to effectively target them.

Though his call to ban Muslims has drawn accusations that he is fomenting bigotry, Trump said his policies were instead geared toward national unity and fighting an ideology that promotes oppression of women and gays. He called on sending home those who preach hate.

But he also cast suspicion even on second-generation immigrants, saying their status, along with those born in other countries, was a common thread in several terrorist attacks. That group of Americans with foreign-born parents would include Trump, whose mother was born in Scotland, and his youngest child, ­Barron, whose mother, Melania Trump, was born in the former Yugoslavia.

Trump, who has vacillated in recent days on his incendiary charge that Obama and Clinton were founders of ISIL, attempted to modify that assertion Monday. Instead of calling them the literal founders, he said that the rise of the terrorist group "is the result of policy decisions made by President Obama and Secretary of State Clinton." He singled out the withdrawal from Iraq.

Trump also asserted that Libya, Syria, Egypt, Iraq and Iran all posed lesser threats before Obama took office. Trump did not speak of his former support for the interventions in Libya and Egypt that he now calls disastrous.