epublican presidential nominee Donald Trump embraces former New York City Mayor Rudolf Giuliani at a campaign rally in Greenville, North Carolina, U.S., September 6, 2016. Reuters

President-elect Donald Trump hasn’t yet formally announced who will be in his cabinet, but several major outlets are reporting that Rudy Giuliani is a favorite for secretary of state.

That would put Giuliani in a position to approve arms transfers to countries that helped make him rich after he termed-out as mayor of New York and began working in the private sector nearly 15 years ago.

Before joining Trump’s crusade to “drain the swamp,” Giuliani had a lucrative career as a lobbyist, lawyer and consultant in the private sector. He represented Purdue Pharma LP — which makes the painkiller OxyContin —and has worked for law firms that represent the Venezuelan state oil company, the chewing tobacco lobby, and the casino industry.

He's also forged ties with some U.S. allies in the Middle East. His own security consulting business, Giuliani Partners, won a contract to help train the security forces of Qatar in 2005, and that same year Giuliani joined the Bracewell law firm in Houston — a longtime lobbyist for the government of Saudi Arabia.

Giuliani has never revealed the value of those business relationships with the oil-rich Gulf States. But when he ran for president in 2008, financial disclosure forms showed that he earned over $4 million from Giuliani Partners that year, and pulled in another $1.2 million from his work at Bracewell.

In January 2016, Giuliani left what had become Bracewell & Giuliani to join the law firm Greenberg Traurig, a major lobbyist for the private prison industry. He's still at the helm of Giuliani Partners and its subsidiary Giuliani Security and Safety; the full client list for both companies has never been made public.

As secretary of state, Giuliani would likely be tasked with overseeing multi-billion dollar weapons transfers to former clients Qatar and Saudi Arabia. The secretary of state, through the assistant secretary for political-military affairs, must approve all foreign military sales — even those undertaken by a private defense contractor. In September, for example, the Obama administration signed off on a $4 billion sale of 72 Boeing F-15E Strike Eagles to Qatar, and a $1.2 billion deal to sell Abrams M1A1 tanks to Saudi Arabia.

Giuliani’s former clients are likely to be on the receiving end of new arms deals under a Trump administration. During the election season, Trump pledged to outsource much of the U.S. campaign against the Islamic State group to U.S. allies in the region. Making good on that promise would require resupplying the major anti-ISIS powers in the Gulf: Qatar and Saudi Arabia.

Giuliani would not be the first secretary of state to face potential conflicts of interests in foreign military transfers. As the top U.S. diplomat between 2008 and 2013, Hillary Clinton approved $165 billion in sales to 20 nations whose governments have given money to the Clinton Foundation, according to an International Business Times analysis.