Bush was most comfortable when criticizing the Obama White House. He said the U.S. has been a necessary leader because "our presidents, both Republicans and Democrats, have accepted responsibility in the world with a faith that America is a force for good. I have doubts whether this administration believes American power is such a force."

Bush said he favored Israeli Prime Minister Benjamin Netanyahu speaking to Congress, and in general complained of chilly relationships with allies. "The great irony of the Obama presidency is this: Someone who came to office promising greater engagement with the world has left America less influential in the world," Bush said. In particular, he assailed the White House's policy on Iran: "They draw red lines, then erase them. With grandiosity, they announce resets and disengage."

Lurking not far behind these questions is the memory of George W. Bush. Why, as Jeb Bush noted, does Iran now hold so much sway in Damascus, Sanaa, Baghdad, and Beirut? One major reason is that the war in Iraq created a power vacuum that empowered Tehran. How effectively did George W. Bush slow down Iranian proliferation? Not very.

All of that would be much easier to shake off if it was clearer how he differed—and if his circle of advisers wasn't so similar to George W. Bush's. (Much of that overlap is surely attributable to the small size of foreign-policy circles; Obama's administration drew heavily on Clinton aides, especially early on, but he's conducted a very different policy.) Without taking more concrete stands, however, that's hard to discern.

For example, Bush's critique of Obama's quickly abandoned red lines on Syria hits the mark. But what would Bush have done? Would he have bombed Syria? Would he have asked for congressional approval? It's not clear. He blasted the White House for not imposing greater penalties on Russia for invading Ukraine. His only prescription was to arm the government there, calling the failure to do so "feckless."

Some of the speech seemed to be aimed as much at Rand Paul, a presumed rival for the Republican nomination, from the emphasis on projecting American power abroad to his defense of the NSA's metadata-collection program. "We do protect our civil liberties, but this is a hugely important program to keep us safe," Bush said. And his call for increased military budgets seems risky, since the U.S. already spends more on the military than other developed countries, and since polls suggest Americans don't want more Pentagon spending. Of course, if Bush could deliver the 4 percent annual growth he wants—and it's unlikely—no one would object. (His suggestion that the U.S. should become one of the BRICS, an acronym to describe emerging economies, is mostly confusing.)

Perhaps most importantly, Bush's speech sets him up nicely against Hillary Clinton. For all the vagueness of his address, it still offered a clearer articulation of a worldview than the presumptive Democratic nominee has done. Bush is also somewhat insulated from any attacks on his brother's misadventures in the Middle East, since Clinton both voted for the war and helmed the Obama administration's policy in the region as secretary of state.

As a result, Bush's speech did a good job of differentiating him from Obama, Paul, and Clinton, even as it did little to fulfill its apparent intention of showing how he's different from his famous relations. But it's a long campaign, and you can't do everything in one speech.