It came as no surprise to me that Wisconsin Gov. Scott Walker dazzled the audience at the recent Iowa Freedom Summit.

I have long touted the potential strength of Walker as a presidential candidate. He has an impressive record of actual governing accomplishments and has advanced conservative ideas in the face of fierce opposition from unions and liberal activists nationwide. He’s also demonstrated clear political skill in winning three elections in four years in a blue state. At a time of division among Republicans, it’s hard to think of another candidate who can excite conservatives as much as Walker without giving nightmares to party elites.

I also never really understood where the idea developed among the Beltway media that he was too boring, as over the years I’ve frequently seen Walker energize conservative crowds when he needed to. All of Walker's best attributes as a candidate were on display in Iowa, as he spoke with fire in his belly, articulating a firm conservative message that was backed up by his record of success and communicated in an affable and relatable manner.

So, having talked up Walker’s chances when many were underestimating him, I think it’s worth offering a note of caution now that that everybody else has realized he’s been underestimated.

For Walker to realize his potential as a candidate, he will have to get serious about foreign policy.

This isn’t to say that Walker, to date, has said or done anything particularly embarrassing when it comes to foreign policy. But for perfectly understandable reasons — advancing ambitious reforms in a state while running for election three times in four years — he hasn’t had the time or cause to do much studying of national security issues until now.

Working against Walker is the fact that he had to run for reelection last year and is only expected to announce his candidacy in the summer, after a busy legislative session. In contrast, Walker’s key rivals for the Republican nomination either have some foreign policy background by virtue of serving in Congress, or have had enough time since their last election campaigns to prepare for foreign policy questions during a presidential run.

Last March, when I had a chance to interview Walker, I asked him about foreign policy, and was able to get a general idea of where he was coming from. Walker’s sensibility is close to where I suspect most Republicans are today — they don’t necessarily want to intervene in every conflict, but they don’t like to see America pushed around on the world stage, either.

At the time, Walker criticized Obama’s retreat from his “red line” on Syria. “I'm not necessarily encouraging that we draw red lines all over the place,” he said. “My sense is just, you shouldn't point a gun at somebody if you're not prepared to shoot.”

Walker also referenced Ronald Reagan’s firing of the illegally striking air traffic controllers early in his presidency. “When Ronald Reagan took that action against the air traffic controllers, that in my mind was the beginning of the end of the Cold War,” Walker told me. “And the reason was, from that point forward nobody doubted how serious Ronald Reagan would be as president. Our allies knew that they could trust him, that he was rock solid. Our adversaries knew not to mess with him. And even though he presided over an incredible buildup in our nation’s national defense, in our military, we had very few, very limited military engagements during his eight years as president.”

It’s clear how this could translate into a presidential campaign theme for Walker — like Reagan, he was willing to stand firm during his conflict with public sector unions, and as president, unlike Obama, he’d be able to project strength and proudly defend American values abroad.

This much was clear in his speech in Iowa. Though he didn’t focus much on foreign policy, Walker did say toward the end of his speech, “We need a president who doesn’t sit in Washington, D.C., when world leaders are standing together against terrorism in Paris. We need a president and leaders in Washington — we need leaders who understand that when freedom-loving people anywhere in the world are under attack anywhere else, they’re under attack against all of us who believe in freedom.”

At this early stage, he can get away with such broad declarations. But as soon as he’s a declared candidate, he’s going to start being asked to elaborate on his foreign policy views with much more specificity. And all it will take is one early slip up — say, referring to the Sunni nation of Iran — to cement the idea that he isn’t ready for prime time.

Should he emerge as the Republican nominee, Walker would also need to prepared to aggressively attack the failures of Hillary Clinton’s service as Secretary of State, assuming she's the Democratic nominee.

More important than any political calculations, Walker will need to gain a better understanding of foreign policy, because as president, Americans would be putting the nation's security in his hands. The world has become a much more dangerous place during the Obama administration, and America desperately needs strong and effective leadership.