By Carol E. Lee, & Damian Paletta, Wall Street Journal–

The assassination of Russia’s ambassador to Turkey and the apparent terror attack on a Berlin Christmas market underscore the global tinderbox President-elect Donald Trump is set to inherit in coming weeks, and his initial response suggests his White House will take a sharply different approach to such unexpected crises.

Mr. Trump’s written statements just hours after the incidents were a notable contrast from those coming out of the Obama White House.

He labeled the assassin in Ankara a “radical Islamic terrorist,” even though Turkish authorities hadn’t yet drawn conclusions about the gunmen’s possible affiliations or motivations, whereas the White House simply stressed President Barack Obama’s “determination to confront terrorism.” Mr. Trump called the Berlin ambush a “horrifying terror attack,” while the White House called it a “horrific incident” that “appears to have been a terrorist attack.”

“It’s a completely different style for better or for worse,” said Lorenzo Vidino, director of the program on extremism at George Washington University, adding there are upsides and downsides to both approaches.

© DON EMMERT/AGENCE FRANCE-PRESSE/GETTY IMAGESJames Jeffrey, who served as Mr. Obama’s ambassador in Iraq and is now a scholar at the Washington Institute for Near East Policy, pointed to Mr. Trump’s immediate use of the term “Islamic” terrorism, contrasted with Mr. Obama’s steadfast refusal to link Islam with extremism—something Mr. Trump frequently criticized during his campaign.

“With Obama you get thoughtfulness, but you don’t get any decisiveness. You don’t get any anger. You don’t get any passion. And I think people need a little bit of that,” Mr. Jeffrey said.

The events in Berlin and Ankara unfolded as Mr. Trump has yet to articulate clear prescriptions for a host of foreign policy challenges in the Middle East, Europe and Asia, and as his posture so far toward Russia has raised concern among U.S. allies and lawmakers in Congress.

The violence was an early reminder of a lesson Mr. Obama learned repeatedly: The only guarantee for a sitting commander-in-chief is that world events are sure to intervene and distract from any set agenda.

Mr. Trump’s aides didn’t respond to questions about on what information he was basing his statements on Berlin and Ankara. White House officials said they weren’t aware that Mr. Trump would have different or more concrete information than the president on the motivations or background of the perpetrators of the attacks.

On Monday, Russian Ambassador Andrey Karlov was assassinated by a Turkish policeman who opened fire at an art opening in Ankara while denouncing Moscow’s role in the conflict in Syria. Later, a truck driver killed 12 people after plowing into shoppers in Berlin in what German Chancellor Angela Merkel said was believed to have been a terrorist attack.

Other foreign policy challenges have unfolded since Mr. Trump won the Nov. 8 election, including a provocation from China last week and an escalating standoff with Russia over a U.S. intelligence assessment that Moscow used cyberattacks to influence last month’s presidential election.

On Friday, U.S. officials said a Chinese navy vessel nabbed a U.S. drone in the South China Sea, an act that drew a protest from the White House and appeared to infuriate Mr. Trump, who called it an “unprecedented act” in a Twitter post. Mr. Trump also has questioned the intelligence assessment on Russia’s involvement in the cyberattacks.

Jon Alterman, a senior vice president at the Center for Strategic and International Studies and director of its Middle East program, said a president has to be able to simultaneously balance all the various threads of threats.

“Are you protecting people from nuclear Armageddon? Are you protecting people from hostile governments attacking your allies? Are you protecting people from terrorism at home?” Mr. Alterman said. “You need different things to do each of those, but we need all of them.”

Each of Mr. Trump’s past three predecessors has had to contend with terrorist attacks inside the U.S. The 1993 World Trade Center bombing occurred one month after President Bill Clinton’s first inauguration; the 2001 terror attacks occurred eight months after President George W. Bush took office; and separate shootings in San Bernardino, Calif., and Orlando, Fla., occurred in December 2015 and June 2016, during the Obama administration.

John Cohen, a professor at Rutgers University and the former counterterrorism coordinator at the Department of Homeland Security, said Mr. Trump will enter the White House at a time when the U.S. and Europe are confronting the most complex terrorism threats the world has seen and simplifying them may not be sufficient.

“On the one hand, there seems to be a lot of interest by some to frame it in some overly simplistic way using terms like ’Islamic radical terrorism,’ but on the other hand it’s a very different threat than what our traditional counterterrorism authorities are used to facing,” Mr. Cohen said.

On the campaign trail, Mr. Trump pressed foreign countries to take more responsibility for their own defense, said he would temporarily ban the entry of people from countries like Syria and Iraq into the U.S., and promised to be more confrontational with China on issues such as trade and national security. Since he won the election, he has spoken more favorably about working with traditional allies in Europe and Asia.

Mr. Trump has filled key posts on his foreign policy team with retired generals, appointing them as his national security adviser, secretary of Defense, and secretary of Homeland Security. His pick for secretary of State, Rex Tillerson, has built a career making foreign business deals but hasn’t had to intervene in civil wars or for humanitarian crises. Foreign policy experts believe Mr. Trump has assembled an unconventional team that will face tests immediately after taking office.

Mr. Trump receives intelligence briefings several times a week, though not daily as Mr. Obama has. He also is briefed by his national security adviser, retired Lt. Gen. Mike Flynn, the former head of the Defense Intelligence Agency.

Mr. Obama, who was briefed Monday on the Russian ambassador’s assassination while on vacation in Hawaii, often has struggled with balancing his foreign policy agenda against unexpected events.

Throughout his presidency, his goals frequently have been overshadowed by world events—particularly as he has tried to place reduced emphasis on the Middle East and more on implementing a so-called U.S. pivot to Asia.

The attacks in Paris in 2015 unfolded, for instance, as Mr. Obama was set to travel to Asia for summits intended to focus on his trade policy and efforts to strengthen U.S. ties in the region.

The dynamic has played out with regularity, including in 2014 when the crisis in Ukraine distracted from his agenda on a trip to Mexico, and at home where he has faced questions about his approach to Syria while trying to focus attention on the merits of his significant reduction of the number of U.S. troops serving in combat overseas.

Most recently, in November after campaigning aggressively against Mr. Trump, Mr. Obama embarked on the final overseas swing of his presidency intending to showcase his legacy in Asia and Latin America. But that trip was overshadowed by the election of Mr. Trump.

Write to Carol E. Lee at and Damian Paletta at