Two things: Gerson is a Left, Lib writer for the way too left leaning Washington Post.
Second, the WAPO is a newspaper that under the Graham family leadership prided itself and held a reputation for somewhat balanced journalism. Under its ownership by Jeff Bezos of Amazon, since he purchased the paper a few years ago, it has become less credible and has moved decidedly Left. What was once a great newspaper has turned in its' long-earned bona fides for circulation numbers. 
Addressing the article, no president in my 60 year lifetime has made the US less safe, second only to Kennedy. Kennedy, you may remember, was sized up by Khrushchev in their Vienna summit as shallow and weak, which led directly to Russia moving missiles into Cuba. See below. 
http://www.nytimes.com/2008/05/22/opinion/22thrall.html
We experienced the same when Obama decided to disengage on the world scene and after he reneged on his "red line" in Syria, then came Crimea and the South China Sea by Russia and China.