Who is Trump’s new security advisor?

A native of Baltimore, Bolton, 69, received undergraduate and law degrees from Yale University. Between stints in private practice, he took a series of increasingly important jobs in government, starting at the U.S. Agency for International Development under President Ronald Reagan and later as an assistant attorney general.

After the 2000 election, Bolton joined the Republican legal team in Florida during the recount battle between Bush and Vice President Al Gore. After the Supreme Court halted the recount, resulting in Bush’s victory, Dick Cheney, the new vice president, persuaded the incoming secretary of state, Colin L. Powell, to make Bolton an undersecretary in charge of arms control. In that role, he helped pull the United States out of the Anti-Ballistic Missile treaty but negotiated a separate treaty with Russia paring nuclear arsenals.

When Condoleezza Rice succeeded Powell, she rebuffed pressure from Cheney to make Bolton her deputy. Bush nominated him for the U.N. post, but key Republicans opposed him, including a former assistant secretary of state who testified that Bolton was a “kissup, kick-down sort of guy”who abused underlings.

After the Senate refused to confirm Bolton, Bush gave him a recess appointment instead — a decision he would come to regret. Bolton clashed regularly with Rice and, after leaving office, broke with Bush over what he saw as weak-kneed policies on North Korea and Iran.

At one point, Bolton toyed with running for president himself, only to back off. Instead, he created an organization to support like-minded candidates.

His super PAC was one of the earliest customers of Cambridge Analytica, which has found itself confronting a deepening crisis after reports this past weekend that the firm had harvested the data from more than 50 million Facebook profiles in its bid to develop techniques for predicting the behavior of individual U.S. voters.

The firm was founded with a $15 million investment from Robert Mercer, the wealthy Republican donor who has backed both Bolton’s PAC and Trump. Cambridge’s so-called psychographic modeling techniques, which were built in part with the data harvested from Facebook, underpinned its work for the Trump campaign in 2016, setting off a furious debate about the merits of the firm’s methods. The same techniques were also the focus of its work for Bolton’s PAC.

Using psychographic models, the company designed advertisements for candidates supported by Bolton’s PAC, including the 2014 campaign of Thom Tillis, the Republican senator from North Carolina. One advertisement, a video that was posted on YouTube, was aimed at fearful and neurotic voters — it emphasized security and the idea that Tillis could keep America safe.

Bolton also recorded a video used by a Russian gun rights group in 2013 to encourage Moscow to loosen gun laws, according to a report by NPR.