Jardine Lloyd Thomp-son Group P.L.C.'s 2014 re-entry into the U.S. retail market likely will prove to be a seminal moment in the company's history.

The London-based insurance, reinsurance and employee benefits brokerage merged two of its divisions — JLT Specialty Ltd. and Lloyd & Partners Ltd. — last August.

JLT said the move, which followed its late-2013 acquisition of Towers Watson & Co.'s reinsurance business, signaled an expansion of the broker's U.S. activities across its specialty areas, including energy, construction, financial lines, credit, political and security risk, and aerospace business.

If the U.S. expansion is successful, it will be “transformational for the group,” said Eamonn Flanagan, head of the Liverpool, England, office of investment banking consultant Shore Capital Group Ltd.

JLT's Dominic Burke said that one of the first things he did when he became CEO in 2006 was to divest the broker's U.S. retail business because he believed it did not have the “financial clout” at that time to compete with larger U.S. retail brokerages and that having a U.S. retail arm seemed “confusing” for a company with a “wholesale heritage.”

But as JLT grew over the years, he said it also became clear that clients — whatever their size — were becoming more global and needed global brokerages to service their needs. “So, perhaps there was an inevitability that we would return” to the U.S. retail market, Mr. Burke said.

The opportunity to do so followed the acquisition of Towers Watson Re, now rebranded into JLT Re, Mr. Burke said.

When it acquired Towers Watson Re, JLT said in a statement that the deal would give its reinsurance brokerage operation combined revenues of about $266 million. For the year ended June 2013, Towers Watson Re posted revenue of about $166 million.

The acquisition also meant that JLT now had office space, information technology systems, staff and other functions in the United States, which meant it would not have to grow its specialty retail operations from scratch, he said.

In the meantime, the brokerage has been able to attract talented brokers and managers, Mr. Burke said. They include JLT Specialty Insurance Services Inc. CEO Michael Rice and President and Deputy CEO Pat Donnelly, both of whom joined from Aon P.L.C.; and Jim Pierce, chairman of JLT's U.S. specialty business, who joined from Marsh L.L.C.

“We are going to build a business that is specialized and very focused on what it wants to be, aligned with our global specialisms,” Mr. Burke said.

He said he's been “truly delighted” by clients' reactions to the move and is confident that, over time, JLT can build a “great business” in the United States.

“We've arrived on the shores of the United States. We've burnt our boats, and we are not going back,” Mr. Burke said.

But expanding to the U.S. is “a big move and not without its risks,” said Shore Capital's Mr. Flanagan.

The U.S. expansion “puts JLT right in the heart of the footprint of the big three” brokers in the United States, he said.

That could be challenging since the largest three brokers — Aon, Marsh and Willis Group Holdings P.L.C. — are much bigger than JLT in the United States, he said.

JLT, the world's No. 5 broker, is the 15th-largest broker of U.S. business in the 2015 Business Insurance rankings.

In addition, Mr. Flanagan said, JLT now is in competition with some U.S. brokers it used to service via its wholesale capabilities.

While the loss of that wholesale business could put about $50 million of revenue at risk, “the potential and the opportunities far outweigh those risks,” he said.

Not only is the U.S. expansion taking place when U.S. gross domestic product is once again growing, the Towers Watson Re acquisition, which Mr. Flanagan described as “a fantastic deal in its own right,” gave JLT a physical U.S. presence when Mr. Burke decided to “push the button” to return to the market.

Its U.S. operations now employ more than 100 people and continue to recruit talented people, Mr. Burke said.

Overall, JLT now is a more balanced company, with about 20% of its revenue derived from reinsurance and 26% from employee benefits operations, he said.

This counterbalance helps JLT face headwinds such as insurance overcapacity and foreign exchange rate challenges, he said.

“Our strategy is clear. We want to be a specialist powerhouse,” Mr. Burke said.