President Trump said he has ordered Homeland Security to “step up” the vetting of immigrants in light of Tuesday’s attack.

“I have just ordered Homeland Security to step up our already Extreme Vetting Program. Being politically correct is fine, but not for this!” Trump tweeted Tuesday night.

Earlier in the day, Trump vowed to keep ISIS out of America.

“We must not allow ISIS to return, or enter, our country after defeating them in the Middle East and elsewhere. Enough!” Trump tweeted.

“My thoughts, condolences and prayers to the victims and families of the New York City terrorist attack. God and your country are with you!” Trump tweeted shortly after the attack.