NEW YORK: Aon Plc and Willis Towers Watson Plc on Monday called off a $30 billion merger that would have created the world’s largest insurance broker, saying objections by U.S. regulators created unacceptable delay and uncertainty.

The decision was hailed by some as an early victory for the Biden administration’s Department of Justice, which sued last month to block it. But it stood at odds with European regulators who recently approved the deal, on condition the companies sell assets - deals now halted that will largely affect the proposed buyer, broker Arthur J. Gallagher & Co.

Combining Aon and Willis, which rank second and third in revenue behind Marsh & McLennan Cos Inc, would have created a new leader with $20.3 billion in annual revenue, compared with $17.2 billion for Marsh.

Aon will pay a $1 billion termination fee to Willis, the timing and financial impact of which was not immediately clear. Aon reports second-quarter results on Friday. Willis said on Monday it would boost share repurchases by $1 billion.