Arguably among the most controversial policies of President Donald Trump's first term, though it was ultimately upheld by the Supreme Court, was the so-called travel ban that restricted entry into the U.S. for individuals from certain particularly dangerous nations around the world.

On Wednesday, Trump issued an executive order to impose a new travel ban that targets nearly 20 countries that are either terrorism hotspots, refuse to accept deported nationals, tend to overstay visas illegally, or lack sufficient information for background checks or criminal records, according to Fox News.

White House Deputy Press Secretary Abigail Jackson told the outlet about the new travel ban, "President Trump is fulfilling his promise to protect Americans from dangerous foreign actors that want to come to our country and cause us harm."

New travel restrictions imposed against certain foreign nations

In an executive order on Wednesday, President Trump took action to protect the American people against foreign nationals from 19 particular countries who posed a potential threat of terrorism or were a possible risk to national security and public safety.

In making the determinations, Trump revealed that he "considered various factors, including each country’s screening and vetting capabilities, information sharing policies, and country-specific risk factors -- including whether each country has a significant terrorist presence within its territory, its visa-overstay rate, and its cooperation with accepting back its removable nationals."

That ultimately resulted in the creation of two categories of nations that are subject to either a total ban on the entry of immigrants and non-immigrants alike, as well as a slightly less restrictive suspension that is only applicable to certain individuals -- albeit with some notable specific exceptions.

In the full suspension category are Afghanistan, Burma, Chad, the Republic of Congo, Equatorial Guinea, Eritrea, Haiti, Iran, Libya, Somalia, Sudan, and Yemen.

Nations now facing partial limitations on entry into the U.S. include Burundi, Cuba, Laos, Sierra Leone, Togo, Turkmenistan, and Venezuela.

Trump explains his new travel ban order

In a video posted on Wednesday to Truth Social, President Trump warned of the "dangers posed to our country by the entry of foreign nationals who are not properly vetted, as well as those who come here as temporary visitors and overstay their visas. We don't want them."

"In the 21st century, we’ve seen one terror attack after another carried out by foreign visa overstayers from dangerous places all over the world," he continued. "Thanks to Biden’s open-door policies, today there are millions and millions of these illegals who should not be in our country."

Trump asserted that his first-term travel ban was "one of our most successful policies" that he attributed to the lack of any "major foreign terror attacks on American soil."

"Very simply, we cannot have open migration from any country where we cannot safely and reliably vet and screen those who seek to enter the United States," the president said. "That is why today I am signing a new executive order placing travel restrictions on countries including Yemen, Somalia, Haiti, Libya, and numerous others."

Travel restriction list is subject to change

President Trump observed that the list of nations facing travel restrictions would be periodically reviewed and revised, if necessary, with some countries being removed and new ones added, depending upon circumstances and a variety of factors.

"But we will not allow people to enter our country who wish to do us harm, and nothing will stop us from keeping America safe," he added.