Israeli military prosecutors say the army's much-criticised deployment of cluster bombs in last year's Lebanon war was legal under international law.
Many bomblets fail to explode and continue to endanger civilians
The Israeli army announced there would be no indictments against officers who used them, after a year-long enquiry.
"The use of the weaponry was a concrete military necessity," a statement said.
The UN called Israel's cluster bombing "shocking and immoral", as most were used in the last 72 hours of fighting when a resolution was clearly imminent.
According to the inquiry by the head of the army's Defence College, the majority of cluster bombs were dropped in open areas and their use in urban areas was an "immediate response" to target areas that were being used as launch pads by Hezbollah guerrillas.
The findings were accepted by the army's Judge Advocate General Avihai Mandelblit.
The UN says about four million cluster bomblets were dropped on Lebanon during the 34-day conflict.
Many of them failed to explode on impact, posing a danger to civilians in their homes, gardens and fields.
More than 30 people have been reported killed by cluster bomb and land mine explosions since the 2006 war.
Although cluster bombs are not illegal under the laws of war, campaigners say their use in populated areas constitutes an indiscriminate attack on civilians.