Visiting Germany in May, former President Barack Obama referred to German Chancellor Angela Merkel as one of his "favorite partners."

The German leader, he said, is someone who has "done outstanding work, not just here in Germany, but around the world."

That may have been true once, but no longer. These days, Merkel's Germany is an increasingly unreliable U.S. ally.

As a case in point, on Friday, Merkel gave an extraordinary answer to a simple question. As Politico reports, asked whether Germany would "stand by the U.S. in case of war" with North Korea, Merkel was noncommittal. Instead, she implicitly attacked Trump, stating, "I consider an escalation of rhetoric the wrong answer." Merkel added "I do not see a military solution to this conflict."

With those words Merkel showed gross disrespect to the U.S. and undermined Trump's efforts to encourage China to pressure North Korea to abandon its ballistic missile program.

On the first count of disrespect, Merkel owes the U.S. far better. After all, thousands of U.S. military personnel continue to be stationed in Germany to defend that country from a Russian attack. The U.S. makes that effort without any reciprocity from Germany, which continues to spend just 1.3 percent of GDP on defense. That's far below the 2 percent of GDP target rate for NATO member states.

In consequence, Europe's wealthiest nation has a military force that is largely incapable of projecting power.

It gets worse. In a recent poll, just 40 percent of Germans said their nation should support NATO in defeating a Russian invasion of Europe. Germans are happy for America to spend vast sums and risk its personnel to defend their country, they just don't want to help bear the burden. Nor, as proved by their opposition to U.S. sanctions on Russia, do Germans accept the need to diversify their energy economy.

Put simply, this state of affairs is an unfunny joke.

Yet if nothing else, Merkel should have pledged her support to the United States on the North Korea crisis. Her failure to do so is inexcusable.

Still, Merkel is at least better than her political opponents. With elections in September, the German socialist party has actually pledged not to meet the 2 percent spending target. The U.S. should state that if that party wins, Germany's relationship with NATO will have to be altered.

Alliances are supposed to be about shared sacrifices. Unfortunately, at present, the U.S.-German alliance is very one sided.

At least we have Poland.