President Donald Trump broadened Tuesday a travel ban to prohibit entry into the U.S. by Palestinian Authority passport holders and travelers from seven additional countries, including Syria.

The latest move brings to nearly 40 the number of countries whose citizens face restrictions in coming to the U.S. solely by virtue of nationality, with Trump also tightening rules for routine travel from Western nations.

It comes as Trump, who has long made hostility to immigration a signature issue, orders mass deportations and takes an increasingly strident tone against non-white new Americans.

The White House, in a proclamation, said it was banning foreigners who "intend to threaten" Americans.

Trump also wants to prevent foreigners in the U.S. who would "undermine or destabilize its culture, government, institutions or founding principles," the proclamation said.