Obama condemns 'vicious, calculated and despicable attack' in Dallas

US President Barack Obama on Friday denounced the "despicable" attacks in Dallas in which snipers shot dead five police officers during a protest against police shootings of black men.

"There has been a vicious, calculated and despicable attack on law enforcement," Obama said during a press conference at a NATO summit in Warsaw, adding that the officers were "targeted" by multiple suspects.

“We will learn more undoubtedly about their twisted motivations, but there’s no justification for these kind of attacks or any violence against law enforcement,” Mr Obama said.

“They were targeted while doing their jobs – keeping people safe during a peaceful protest.

The entire city of Dallas is grieving, police across America – which is a tight-knit family – feels this loss to their core, and we are grieving with them,” he said.

Mr Obama described the attack as a “tremendous tragedy”.