The immigrant from Uzbekistan who drove a rented truck into the New York City crowd this week illustrates the extreme difficulty in fighting this war on international terrorism.

How does the United States prevent a lone wolf who enters this country legally — even if he’s been through “extreme vetting” — from committing the act of terror we saw in New York?

Donald Trump says the nation is going to end the visa lottery program that enabled the suspect to enter the country in 2010. Of course, as is the president’s tendency, he has politicized the issue by blaming Democrats for their so-called lax immigration policy; he ignores the fact that the law under question was signed by Republican President George H.W. Bush.

My point on this matter is that lone wolf attacks are going to occur despite our best and most diligent efforts to root out evil doers before they commit their terrible act.

I say this also as someone who supports the president’s desire to implement an “extreme vetting” policy for those seeking to come to this country.

But let us not forget, too, that homegrown Americans are capable of committing infamous and dastardly acts. The Las Vegas massacre this summer; the Oklahoma City bombing in 1995; the Sandy Hook Elementary School massacre; the Charleston, S.C., church slaughter? All of those evil men were native-born, corn-fed Americans; they only represent a fraction of the carnage committed by American-born terrorists.

The Uzbek suspect came here under an existing policy. There reportedly was no sign that he harbored pro-Islamic State sympathies. He became radicalized while living among Americans.

Then he took out his rage. This is why the war against international terrorism is so damn difficult to wage.