WASHINGTON, June 5, 2025 (AFP) - US President Donald Trump signed a new travel ban Wednesday targeting 12 countries including Afghanistan, Iran and Yemen, reviving one of the most controversial measures from his first term.

Trump said the measure was spurred by a makeshift flamethrower attack on a Jewish protest in Colorado that US authorities blamed on a man they said was in the country illegally.

The ban targets nationals of Afghanistan, Myanmar, Chad, Republic of the Congo, Equatorial Guinea, Eritrea, Haiti, Iran, Libya, Somalia, Sudan and Yemen.

Trump also imposed a partial ban on travelers from seven countries: Burundi, Cuba, Laos, Sierra Leone, Togo, Turkmenistan and Venezuela.

Both go into effect on Monday, the White House said.

"The recent terror attack in Boulder, Colorado has underscored the extreme dangers posed to our country by the entry of foreign nationals who are not properly vetted," Trump said in a video message from the Oval Office posted on X.

"We don't want them."

Trump compared the new measures to the "powerful" ban he imposed on a number of mainly Muslim countries in his first term, which caused huge travel disruption across the world.

The US leader said that 2017 ban had stopped the United States suffering terror attacks that happened in Europe.

"We will not let what happened in Europe happen in America," Trump said.

"We cannot have open migration from any country where we cannot safely and reliably vet and screen. That is why today I am signing a new executive order placing travel restrictions on countries including Yemen, Somalia, Haiti, Libya, and numerous others."

"Being in the United States is a great risk for anyone, not just for Venezuelans," Venezuela's Interior Minister Diosdado Cabello said after the announcement, warning citizens against travel there.

Trump's new travel ban could however face legal challenges, as have many of the drastic measures he has taken in his whirlwind return to office.

- 'Dangerous foreign actors' -

The White House unveiled the new ban with virtually no warning, minutes after Trump had addressed some 3,000 political appointees from his balcony at a celebratory "summer soiree."

Trump also unusually made the announcement with no reporters present. He has unveiled many of his most headline-grabbing policy announcements at signing ceremonies in front of journalists in the Oval Office.

Rumors of a new Trump travel ban had circulated following the attack in Colorado, with his administration vowing to pursue "terrorists" living in the US on visas.

Suspect Mohammed Sabry Soliman is alleged to have thrown fire bombs and sprayed burning gasoline at a group of people who had gathered on Sunday in support of Israeli hostages held by Hamas.

US Homeland Security officials said Soliman was in the country illegally, having overstayed a tourist visa, but that he had applied for asylum in September 2022.

"President Trump is fulfilling his promise to protect Americans from dangerous foreign actors that want to come to our country and cause us harm," White House Deputy Press Secretary Abigail Jackson said on X.

"These commonsense restrictions are country-specific and include places that lack proper vetting, exhibit high visa overstay rates, or fail to share identity and threat information."

Trump's proclamation gave specific reasons for each country in his proclamation, which says it is aimed at protecting the United States from "foreign terrorists and other national security" threats.

For Taliban-ruled Afghanistan and war-torn Libya, Sudan, Somalia and Yemen, it said they lacked "competent" central authorities for processing passports and vetting.

Yemen, where American forces have struck Iranian-backed Huthi rebels, was also the "site of active US military operations," it said.

Iran, with which the United States is in negotiations on a possible nuclear deal, was included as it is a "state sponsor of terrorism," the order said.

For most of the other countries, Trump's order cited an above average likelihood that people would overstay their visas.

Trump separately on Wednesday announced a ban on visas for foreign students who are set to begin attending Harvard University, ramping up his crackdown on what he regards as a bastion of liberalism.