WASHINGTON The Pentagon will send hundreds of additional spies overseas as part of an ambitious plan to assemble an espionage network that rivals the CIA in size, U.S. officials said.

The project is aimed at transforming the Defense Intelligence Agency, which has been dominated for the past decade by the demands of two wars, into a spy service focused on emerging threats and more closely aligned with the CIA and elite military commando units.

When the expansion is complete, the DIA is expected to have as many as 1,600 “collectors” in positions around the world, an unprecedented total for an agency whose presence abroad numbered in the triple digits in recent years.

The total includes military attachés and others who do not work undercover. But U.S. officials said the growth will be driven over a five-year period by the deployment of a new generation of clandestine operatives. They will be trained by the CIA and often work with the U.S. Joint Special Operations Command, but they will get their spying assignments from the Department of Defense.

Among the Pentagon’s top intelligence priorities, officials said, are Islamist militant groups in Africa, weapons transfers by North Korea and Iran, and military modernization underway in China.

“This is not a marginal adjustment for DIA,” the agency’s director, Lt. Gen. Michael Flynn, said at a recent conference, during which he outlined the changes but did not describe them in detail. “This is a major adjustment for national security.”

Merging agencies

The sharp increase in DIA undercover operatives is part of a far-reaching trend: a convergence of the military and intelligence agencies that has blurred their once-distinct missions, capabilities and even their leadership ranks.

Through its drone program, the CIA now accounts for a majority of lethal U.S. operations outside the Afghan war zone. At the same time, the Pentagon’s plan to create what it calls the Defense Clandestine Service, or DCS – which was announced in April – reflects the military’s latest and largest foray into secret intelligence work.

The DIA overhaul – combined with the growth of the CIA since the Sept. 11, 2001, terrorist attacks – will create a spy network of unprecedented size. The plan reflects the Obama administration’s affinity for espionage and covert action over conventional force. It also fits in with the administration’s efforts to codify its counterterrorism policies for a sustained conflict and assemble the pieces abroad necessary to carry it out.

Unlike the CIA, the Pentagon’s spy agency is not authorized to conduct covert operations that go beyond intelligence gathering.

Heightened concerns

The expansion of the agency’s clandestine role is likely to heighten concerns that it will be accompanied by an escalation in lethal strikes and other operations outside public view. Because of differences in legal authorities, the military isn’t subject to the same congressional notification requirements as the CIA, leading to potential oversight gaps.

U.S. officials said that DIA’s realignment won’t hamper congressional scrutiny.

“We have to keep congressional staffs and members in the loop,” Flynn said in October, adding that he believes the changes will help the U.S. anticipate threats and avoid being drawn more directly into what he predicted will be an “era of persistent conflict.”

U.S. officials said the changes for DIA were enabled by a rare syncing of personalities and interests among top officials at the Pentagon and CIA, many of whom switched from one organization to the other to take their current jobs.

Former senior Defense Department officials said that the DIA now has about 500 “case officers,” the term for clandestine Pentagon and CIA operatives, and that the number is expected to reach between 800 and 1,000 by 2018.