WASHINGTON (NEXSTAR) – President Donald Trump announced a new travel ban. The restrictions would impact 19 countries. The White House is pointing to national security concerns.

President Trump is linking last weekend’s attack in Boulder, Colorado to a new round of travel restrictions, a move critics are calling politically motivated.

“We will not allow people to enter our country who wish to do us harm,” said Trump.

President Trump is blocking entry from 12 countries, including Afghanistan, Iran, Haiti, and Somalia and imposing additional restrictions on seven others.

“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,” said Trump.

The president points to the attack in Boulder as proof the U.S. needs stronger immigration controls but the suspect, in that case, is from Egypt, a country not on the list.

“In the 21st century, we’ve seen one terror attack after another, carried out by foreign visa overstayers,” said Trump.

The White House says the man overstayed a visa, something the president argues this ban will help prevent.

“And nothing will stop us from keeping America safe,” said Trump.

The ban takes effect Monday to give airports and agencies time to prepare.