From Washington, this is VOA news. I'm David Byrd reporting. President Obama seeks to reassure Americans after a week of violence.

Mr. Obama's remarks came at the NATO summit in Warsaw following two fatal police shootings of African-Americans and an ambush that left five policemen dead in Dallas.

The president called Dallas sniper Micah Johnson a deranged individual who does not represent blacks in America.

Mr. Obama said Americans of all races and backgrounds are rightly outraged by the deadly attack on Dallas police officers and rightly saddened and angered by fatal police shootings involving two black men in Louisiana and Minnesota.

"And we have to make sure that all of us step back, do some reflection, and make sure that the rhetoric that we engage in is constructive, and not destructive."

Meanwhile in Dallas on Saturday, the people of the city were working through the emotions of Thursday's violence and trying to make sense of the tragedy.

A makeshift memorial for the five slain officers continue to grow. Mayor Mike Rawlings visited that memorial and said the outpouring of love since Thursday's has shown how people really feel about Dallas police.

"That's what makes it great, that's what makes you hopeful that we can do this, that we can move from senselessness, absurdity that's like a Camus novel, to something that has redemption and hope in it. And that's ultimately what we need to do."

There is late word from Dallas at this hour that an anonymous threat has been called in and police have issued a lockdown at police headquarters in that city.

This is VOA news.

President Barack Obama pledged long-term U.S. support for Europe and urged unity at what he said is a "pivotal moment" for the NATO alliance and Europe.

With more on the summit in Warsaw, Luis Ramirez reports.

A show of force and unity at a time of uncertainty not seen since the Cold War, the summit was about quelling nerves and charting a new course.

One of President Obama's top concerns was Britain's exit from the European Union and questions of whether its absence could weaken NATO.

It was called the most crucial summit since the Cold War, a turning point when NATO's focus has shifted from reassuring its members to deterring a more assertive, more aggressive Russia.

NATO's response - a buildup with additional rotating battalions in the Baltic countries and Poland. On Ukraine, calls for more pressure on Moscow.

And finally, leaders here in Warsaw tackled the issue of NATO's long running role in Afghanistan, where continuing violence means the end is not near.

Luis Ramirez, VOA news, Warsaw.

The U.S. State Department on Saturday issued an urgent call for calm in South Sudan after fighting between rival factions in the capital, Juba, killed more than 100 people.

The U.S. statement urges fighters loyal to President Salva Kiir and those backing his rival, current First Vice President Riek Machar, to "disengage and cease fighting."

At least 115 people have been reported killed.

A 2015 peace deal ended a 20-month-long civil war but it has failed to stop unrest in the newly formed country.

Iraqi forces recaptured a northern airbase from the Islamic State group on Saturday, a victory hailed by its prime minister as a key step ahead of the long-awaited operation to retake the northern city of Mosul.

In a statement issued on his website, Iraqi Prime Minister Haider al-Abadi described the airbase in the town of Qayyara as an important base to liberate Mosul.

In the mostly Sunni province of Anbar west of Baghdad, government troops on Saturday consolidated their grip on the provincial capital of Ramadi, which was retaken from the Islamic State last year.

They captured two villages just north of the city.

A Soyuz space capsule carrying a three-person multinational crew docked with the International Space Station early Saturday.

About 400 kilometers above the earth, NASA astronaut Kathleen Rubins, Russian cosmonaut Anatoly Ivanishin and Japan's Takuya Onishi will spend the next few months on the station.

For more, visit our website. I'm David Byrd in Washington.

That's the latest world news from VOA.