How the presidential candidates are reacting to terrorist attacks in Belgium

WASHINGTON (CNN) — This is not the first time a horrific terrorist attack has rocked the 2016 presidential campaign.

Last November’s strike in Paris ensured that national security would play a central role in the election — emboldening Donald Trump to double-down on his immigration policies, exposing weaknesses in Ben Carson’s knowledge of foreign policy and underscoring Hillary Clinton’s experience on the world stage.

Tuesday’s strike, which unfolded on the same day that voters head to the polls in several Western states, could again inject the fear of terrorism into an already volatile campaign.

Trump, who has linked mainstream Islam to terrorism more explicitly than any other major U.S. politician, told NBC’s “Today Show” that the Brussels attacks were “just the beginning” of an unfolding “disaster” to come.

Republican opponent Ted Cruz, a Texas senator, declared that “radical Islam is at war with us and vowed to defeat it.” And Ohio GOP Gov. John Kasich said President Barack Obama should abandon his trip to Cuba and Argentina and come home to organize allies in a fight against the “enemies of the West.”

Democratic front-runner Hillary Clinton, for her part, issued a statement warning that “vicious killers” bent on spreading “hate and fear” would not win. And Bernie Sanders, a Vermont senator challenging Clinton for the Democratic nomination, said the attacks were a brutal reminder that the world must come together to destroy ISIS.

The candidates’ quick reactions reflected the potency of arguments about terrorism in 2016, posing new challenges and opportunities as Trump seeks to lock down the Republican race and Clinton tries to finally snuff out Bernie Sanders’ campaign.

Political reverberations from the attacks also stole the spotlight from Obama’s historic trip to lay the Cold War to rest in Cuba and threw new scrutiny on his approach to tackling ISIS and terrorism at home and abroad — an examination that has deep implications in the election to find his successor.

Tuesday’s campaign skirmishes recalled the aftermath of the Paris attacks in November, which confirmed that terrorism retains a unique capacity, even thousands of miles away and 15 years after the September 11 attacks, to transform the U.S. political scene.

That rampage by extremist Islamists prompted Trump to promise an uncompromising national security policy and allowed Clinton to showcase her foreign policy knowledge.

But it challenged Sanders, who was out of his comfort zone in liberal, domestic policy and badly exposed Carson, a then-surging Republican, whose campaign never recovered.

The fallout from such attacks — which pose the implicit question of whether a similar outrage could happen on American soil — is not always predictable.

After the Paris attacks in November, the conventional wisdom held that the reverberations would hit Trump — who lacks foreign policy experience and often spurns the nuances of diplomacy — and elevate more seasoned candidates like former Florida Gov. Jeb Bush and Florida Sen. Marco Rubio.

But with his sharpened political instincts, Trump managed to turn the tumult after Paris and a subsequent ISIS-inspired mass shooting in San Bernardino, California, in December to his advantage.

Trump’s call in December for a “total and complete” ban on the entry of Muslims to the United States until it was possible to figure out what was “going on” in the Islamic world shocked the political establishment and horrified the foreign policy brass. But it played into Trump’s core political persona as a truth teller who swipes away political correctness and struck a chord with a certain section of Republican grass-roots voters who have flocked to the billionaire populist.

In fact, Trump credits the changed political atmosphere for his success at a critical moment in the campaign late last year.

“So we started and something happened called Paris. Paris happened. And Paris was a disaster. There have been many disasters, but — it was Paris,” Trump said last week in Florida after a new string of primary victories.

“And what happened with me was, this whole run took on a whole new meaning,” he continued, “and the meaning was very simple: We need protection in our country. And that’s going to happen. And all of a sudden, the poll numbers shot up.”

Trump was playing on some fertile ground. A CNN/ORC poll in December found that a combined 74% of Americans were “not too satisfied” or “not at all satisfied” about progress in the U.S. campaign against terrorism.

And a CBS News poll conducted in early December found that 54% of Republicans favored Trump’s suggestion for a temporary entry ban on Muslims — suggesting that his intervention was popular among GOP primary voters. More moderate rhetoric by Bush and Rubio failed to catch the moment, and they are no longer in the race.

Despite Trump’s success in riding the political wave of the Paris attacks, both Cruz and Kasich now see a chance to portray him as unfit to be president in a dangerous age in the aftermath of the Brussels terrorism.

Cruz immediately seized on Trump’s comments Monday that the U.S. needs to reconsider the level of its involvement with NATO.

“It is striking that the day after Donald Trump called for weakening NATO, withdrawing from NATO, we see Brussels, where NATO is headquartered, the subject of a radical Islamic terror attack,” Cruz told reporters.

He charged, “Donald Trump is wrong that America should withdraw from the world and abandon our allies.”

Kasich’s call for Obama to return home and lead the West also seemed to be playing off Trump’s remark.

However, attacks on Trump’s qualifications to lead the nation at a time of global turmoil have yet to seriously affect his rock-solid support among his faithful Republican supporters.

The commander-in-chief test could prove to be more potent in the general election as a wider span of voters size up a potential president.

Clinton has already begun building a case that Trump is unfit to sit in the Oval Office. And on the face of it, the political uproar following the Brussels attacks should play to the Democratic front-runner’s strengths, given her fluency with foreign policy as a former secretary of state and two-and-a-half decades of experience on the world stage.

After the Paris and San Bernardino attacks, Clinton did prosper in comparison to the more domestically focused Sanders. But liberal primary voters are far less fixated on terrorism and security than those on the Republican side.

Moreover, as the campaign has continued, Sanders has become more adept at addressing national security and has warmed to his theme that his judgment is superior to hers after ill-fated U.S. interventions in Iraq and Libya that she supported.

Even so, in the wake of the Brussels attacks it is likely the former secretary of state will seek to leverage her experience to bolster her image as a potential general election candidate.

Clinton, appearing on CNN Tuesday, sought to portray a statesmanlike image, saying that Europe needed to toughen its own anti-terrorism laws and warned that the attacks underscore the need for unflappable leadership in the White House.

“We need steady, strong, smart minds and hands in the White House, in the Situation Room, to deal with the problems that we face around the world,” Clinton said.

She declined to respond to Trump’s critique that she was not strong enough and lacked the stamina to be president, however, saying his “constant stream of insults” was “absurd.”

Yet the Brussels attacks could bring political problems for Clinton as they renew focus on Obama’s efforts to eradicate ISIS — a campaign that critics say has stuttered because of his reluctance to contemplate large-scale U.S. campaigns in the Middle East and a tendency to withdraw from the world.

Trump’s uncompromising political message also puts pressure on Clinton to show steel to mainstream voters, even though the Democratic base is wary of hawkishness abroad and her record on foreign policy.

GOP denunciations of Obama’s handling of national security, meanwhile, can complicate Clinton’s path to the presidency

A wider critique of the President’s approach is sure to encompass her role in the first-term decisions of his war cabinet — one reason why she frequently mentions how she counseled Obama to launch the raid to kill Osama bin Laden.

And in a broader sense, political developments that drive Obama’s approval rating down complicate Clinton’s case that the Democrats should keep the White House.

The president this month hit a rare 50% approval rating, according to Gallup, a level that historic data suggests is crucial for candidates from the same party seeking to hold on to the presidency.