The high-flying rhetoric in his speech aside, the most troubling part of President Barack Obama’s visit to the United Nations yesterday was his decision to forego meetings with other heads of state gathering at the General Assembly meeting.

What a missed opportunity for tackling a wide array of world problems.

For instance, it was just two weeks ago that the walls of our Cairo embassy were breached and the U.S. flag burned; our consulate in Benghazi was attacked, resulting in the death of our ambassador to Libya.

In light of the “Islamist Spring,” wouldn’t it have made sense for Obama to have sat down with some of the new Middle East’s leaders to discuss his call for rejecting violence and intolerance that has just cost at least four American lives?

Of course, there’s Iran. Tehran’s runaway nuclear (weapons) program is by far the most predictable national security crisis heading in our direction. But our policy has resulted in little to no progress on preventing Iran from joining the once-exclusive nuclear weapons club.

Passing on a meeting with the leader of the other state most affected by Iran’s atomic aspirations, Benjamin Netanyahu, Obama squandered a chance to show solidarity with Israel at a critical time.

And what about Syria — a crisis that has dragged on for 18-plus months and cost more than 20,000 lives? Our inaction has been attributed to a lack of consensus at the U.N., especially among China and Russia at the Security Council. Wouldn’t it have made sense to speak in person with key regional leaders to look for a way to stop the bloodshed?

Many would have liked to see some presidential engagement on Afghanistan, where things have been rough for 60,000 brave U.S. troops fighting the Taliban, the Haqqani Network and al-Qaida.

And some analysts fear territorial disputes in the East and South China Seas could lead to fisticuffs among the likes of China, Japan, and others. Where’s the presidential presence on the Pacific pivot?

It’s not like the president hasn’t taken time in the past to grip and grin at the General Assembly. According to CBS News’ Mark Knoller, Obama held 13 bilateral meetings with leaders at the U.N.’s confab last year.

It’s easy to see why folks say Obama is more interested in running for re-election, including taping “The View” while in New York, rather than being diplomat and commander in chief.

You have to wonder if the president has gone from leading from behind to not leading at all. But these pressing problems, among others, won’t wait until this — or any — U.S. president is interested in engaging on them.

Peter Brookes is a Heritage Foundation senior fellow and a former deputy assistant secretary of defense.