Hong Kong (CNN Business) Masa Son is sticking with Saudi Arabia.

The CEO and founder of Japan's SoftBank ( SFTBF ) on Monday expressed "strong regret" over the killing of Saudi journalist Jamal Khashoggi , but said his company can't sever its financial ties to Saudi Arabia. He said SoftBank wouldn't take any more Saudi cash until the truth about the murder was known.

The Japanese billionaire has built up strong ties with the Saudi government and Crown Prince Mohammed bin Salman. The kingdom provided nearly half the $93 billion that SoftBank raised for its Vision Fund, which has made investments in startups such as WeWork and Slack.

The killing of Khashoggi in the Saudi consulate in Istanbul was "a terrible incident that should never have happened," Son said Monday in his first public comments since an international outcry erupted over the journalist's death.

But SoftBank had "received funds to invest from the people of Saudi Arabia," Son added. As horrific as the killing was, the company believed it should "fulfill its responsibility for the future of the Saudi people," Son said during an earnings presentation in Tokyo.