Donald Trump recently ignited another controversy when he mused that the North Atlantic Treaty Organization was obsolete. He hinted that it might no longer be worth the huge American investment.

In typical Trump style, he hit a nerve, but he then offered few details about the consequences of either staying in or leaving NATO.

NATO is certainly no longer aimed at keeping a huge Soviet land army out of democratic Western Europe, as was envisioned in 1949.

The alliance has been unwisely expanded from its original 12-nation membership to include 28 countries, absorbing many of the old communist Warsaw Pact nations and some former Soviet republics. NATO may have meant well to offer security to these vulnerable new alliance members. Yet it is hard to imagine Belgians and Italians dying on the battlefield to keep Russian President Vladimir Putin’s forces out of Lithuania or Estonia.

Today’s NATO pledges to many of its newer participants are about as believable as British and French rhetorical guarantees in August 1939 to protect a far-away Poland from its Nazi and Soviet neighbors.

No NATO member during the 40-year Cold War invoked Article 4 of the treaty, requiring consultation of the entire alliance by a supposedly threatened member. Turkey has called for it four times since 2003.

The idea that Western Europe, beset with radical Islamic terrorism and unchecked migrations from the war-torn Middle East, would pledge its military support to the agendas and feuds of Turkish President Recep Tayyip Erdogan’s increasingly Islamist and non-democratic regime is pure fantasy.

Few NATO members meet the alliance’s goal of investing 2 percent of gross domestic product in defense spending. Instead, socialist Europe expects the United States to carry most of NATO’s fiscal and military burdens.

Europe is increasingly seen as defenseless against Islamic terrorism, and unable to stop the immigration of legions of young male Muslim migrants from the war-torn Middle East. It is also viewed as a fat target for unstable (and increasingly nuclear) regimes.

Sometimes Europeans even add insult to injury. They count on U.S. subsidies to help trim defense costs in order to fund socialist entitlements — even as they caricature America as an over-militarized superpower bully.

Using NATO forces outside of Europe has not always been productive. It was helpful in Serbia, of questionable utility in Afghanistan, and completely disastrous in Libya.

Is Trump right, then, that we should let NATO die on the vine? Is the alternative of a future without the alliance preferable to the present costly and flawed NATO?

The more things change, the more they stay the same. Lord Ismay, NATO’s first secretary general, said that the alliance was formed “to keep the Russians out, the Americans in, and the Germans down.”

The Soviet Union has collapsed, Germany is now in the European Union, and the EU has a larger population and economy that the United States. But Putin’s Russia is still nuclear and aggressive. It expands anywhere it senses weakness. Germany still earns suspicion in Europe, whether because of Chancellor Angela Merkel’s destructive immigration policies or the equally unwise practice of rich German banks recklessly lending to bankrupt Mediterranean nations. The European Union never managed to unite its disparate nations into something cohesive and similar to the individual states of America.

In sum, a powerful Russia will always have to be watched. A dynamic and headstrong Germany will always have to be integrated into some sort of military alliance. And the United States will always have a natural self-interest in preemptively keeping kindred Europeans from killing each other.

The West is increasingly under assault. It is the target of radical Islamic terrorists, it is losing its deterrence with Russia and China, and it is seen as weak by rogue regimes such as Iran and North Korea.

The issue is not whether NATO is still useful, but whether the alliance can reform itself before it implodes.

NATO must stop growing. Why offer guarantees to nations that it would not protect in the real world — nations that would only become red lines for aggressive enemies that wish to humiliate and unwind the alliance? NATO should be wary of using its forces outside of Europe and should instead outsource such peacekeeping to individual members acting on their own.

Turkey and other members should be warned that autocracy and Islamicization are contrary to NATO principles and are grounds for expulsion.

Greater European military expenditures will not only keep the U.S in the alliance, but also protect Europeans themselves, who lack the two-ocean buffer of the United States.

Constitutional nations with common traditions of freedom of the individual, self-criticism, and tolerance of dissent and difference are becoming rare these days. Without shared military power and cooperation, Westerners can either all hang together or surely we will hang separately.

© 2016 TRIBUNE CONTENT AGENCY, LLC.