WARSAW, Poland — President Obama tried Friday to channel Americans’ horror and outrage over the targeted shootings of police officers, decrying the fatal attack in Dallas as “despicable” and declaring there was no justification for the violence.

“I believe that I speak for every single American when I say that we are horrified over these events, and that we stand united with the people and the police department in Dallas,” Obama said early Friday. He spoke just hours after gunfire killed five officers and wounded seven others during protests over fatal police shootings of black men in Minnesota and Louisiana.

Obama noted the facts are still coming to light but “what we do know is that there has been a vicious, calculated and despicable attack on law enforcement.”

The president’s message was delivered at long distance as he traveled overseas for talks with NATO and European Union leaders. The distance, and the death toll, presented not-unfamiliar problems for this White House: whether to let a mass shooting upend the president’s travel plans and how to participate in a moment of national grief from afar.

Late Friday, the White House announced Obama would cut his trip short by one day. He will attend meetings in Warsaw Saturday, as scheduled, before heading on to Spain, where his itinerary includes meetings with Spanish leaders and a visit with U.S. troops. He will now return to Washington on Sunday, and will visit Dallas at the request of Mayor Mike Rawlings early next week.

The White House has been loath to upend the president’s plans in response to outbursts of violence. In March, Obama attended a baseball game in Cuba hours after a terrorist attack in Belgium spread fear across Europe. The president said altering his plans would have represented a concession to terrorists aiming to disrupt ordinary life.

But the Dallas attack appeared to come with complicating political layers for the president and the potential to mark a different sort of moment.

Combined with the recent shootings in Orlando and the rise in so-called lone wolf terrorism, rising anxiety about public safety could mean the shooting has more enduring impact.

Obama has also aligned himself with civil rights protesters and others calling attention to racial disparities in the justice system, and he has taken some heat from those who cast the movement as anti-law enforcement. The debate has largely split along party lines and stands as a potentially potent issue in the presidential election.

Obama tried to walk a delicate balance in his remarks.

Just hours before gunfire erupted in Dallas on Thursday, the president expressed solidarity with those outraged over police shootings in Baton Rouge and suburban St. Paul. A visibly frustrated Obama urged Americans to push for local law enforcement reforms and said all Americans, regardless of race, should care about the treatment of blacks and Hispanics by police.

Obama argued there’s no contradiction between supporting law enforcement and working to see that biases in the justice system are rooted out.

“So when people say ‘Black Lives Matter,’ that doesn’t mean blue lives don’t matter,” he said, referring to police. “It just means all lives matter – but right now, the big concern is the fact that the data shows black folks are more vulnerable to these kinds of incidents.”

But the president also expressed his gratitude to police officers.

He returned to that theme Friday morning.

“Today is a wrenching reminder of the sacrifices that they make for us,” Obama said. “Today our focus is on the victims and their families. They are heartbroken. The entire city of Dallas is grieving. Police across America, which is a tight-knit family, feels this loss to their core.”

Obama ordered flags flown at half-staff in honor of the victims and he spoke by phone to Rawlings, Dallas Police Chief David Brown and Attorney General Loretta Lynch. He offered his condolences and federal support to the local officials, the White House said.