One of the most important phases of the transition to power for President-elect Donald Trump includes briefings on U.S. intelligence capabilities and secret operations as well as separate descriptions of the extraordinary powers he will have over the military, especially contingency plans to use nuclear weapons, according to officials.

In 2008, after then-President-elect Obama was given one sensitive intelligence briefing at a secure facility in Chicago, he joked, “It’s good that there are bars on the windows here because if there weren’t, I might be jumping out.”

Though Trump has been given some intelligence briefings on threats and capabilities, there are a series of separate briefs scheduled for the president-elect into what Obama has called “our deep secrets.”

Trump spokeswoman Hope Hicks said she could not provide any information on the schedule for the briefings. Previous presidents received them over the course of the entire transition.

First is a detailed look at technical and human intelligence sources and methods that provide critical information on Special Access Programs — the most sensitive top-secret undertakings — for drone strikes and other intelligence operations. This would include the disclosure, if Trump wants the names, of the dozens of officials abroad paid by the CIA, to the tune of millions of dollars. Though entitled, presidents normally have not asked for names unless the secret relationship involves a particularly important CIA asset.

Other methods include the most sensitive technical capabilities of the National Security Agency to intercept communications abroad, store them and make them instantly available to analysts and operators.

Trump will learn that the president is considered “The First Customer” by the intelligence community, which has a tradition of responding to any and every presidential request.

A second briefing will be on the covert actions undertaken by the CIA that are designed to change events abroad without the hand of the United States being revealed publicly. There are currently about a dozen such “Findings” — intelligence orders signed by the president. Some are broad authorities to conduct lethal counterterrorism operations in dozens of countries. Others are narrow, such as support for clandestine efforts in a single country to stop genocide or payments to political opposition or rebels.

Under law and procedures, such covert-action orders are issued by the office of the president, and Obama’s orders will continue unless Trump, as president, changes them. Normally, the president-elect will review current covert actions and decide before the inauguration whether he wants to continue, modify or cease any. He also could add new covert operations after taking the oath.

Obama received his briefing on covert action Dec. 9, 2008.

Under law, the president can decide to launch new covert operations but must inform the Senate and House intelligence committees. For particularly sensitive operations, the president has to see only that the Gang of Eight is informed. The eight are the two party leaders of both the Senate and House, plus the chairman and ranking member of the intelligence committees.

Among the most important “Findings” are counter-proliferation operations designed to prevent a country from obtaining a nuclear weapon or a nuclear weapon delivery capability.

Other operations are offensive aggressive cyberattacks involving stealthy computer hacking designed to break into computer systems of foreign governments. Previously, they have been called the Computer Network Attack (CNA) and are among the most highly secret undertakings of the U.S. government.

In addition, Trump will receive information on domestic counterterrorism overseen by the FBI and Department of Homeland Security. After the 9/11 attacks, the FBI was turned loose to stop the next attack. Efforts to penetrate banks, communications and foreign corporations in the United States have been significantly expanded.

Trump will also be given information about “Continuity of Government,” which are the plans and procedures designed for implementing the line of presidential succession. That could be in case of a terrorist attack or other emergency in which the president dies or could not carry out the duties of his office.

A third briefing will be on nuclear-war plans and options. The “football,” a briefcase carried by the military aide to the president, includes authentication codes designed to ensure that any launch order comes only from the commander in chief.

The “football” also contains a book of options benignly called the “Presidential Decision Handbook.” This top secret/code-word book, known as the “Black Book,” of about 75 pages has separate contingency plans for using nuclear weapons against potential adversaries such as Russia and China.

The president can select nuclear strike packages against three categories — military targets, war-supporting or economic targets and leadership targets. There are sub-options, and the menu allows a president to withhold attacks on specific targets.

Two officials said that the “Black Book” also includes estimates on the number of casualties for each of the main options that run into the millions, and in some cases over 100 million. Officials who have dealt with nuclear-war options said that learning the details can be horrifying and that there is a “Dr. Strangelove” feel to the whole enterprise.

President-elect George W. Bush did not receive his briefing on nuclear options until five days before inauguration in 2001.

Top White House officials say that presidents in the past have had no love and little interest in getting the nuclear war plans briefing and almost recoil at the prospect of having such authority. Under practice as the commander in chief, the president can employ U.S. military forces as he sees fit.

The system of authentication and options is designed for quick response to attack in an emergency. A president might have to make a decision in a matter ofminutes with little or no time to consult the secretary of defense, military leaders or the National Security Council.

In addition, Trump will receive briefings from the Pentagon on current military operations, including the deployments in the ongoing wars in Afghanistan, against the Islamic State and other Special Operations actions abroad.

After one of the briefings in 2008, Obama told a close adviser that it was perhaps one of the most sobering experiences of his life. He said, “I’m inheriting a world that could blow up any minute in half a dozen ways, and I will have some powerful but limited and perhaps even dubious tools to keep it from happening.”

In an Oval Office interview on July 10, 2010, Obama confirmed that he had made that sort of comment.

“Events are messy out there,” he said. “At any given moment of the day, there are explosive, tragic, heinous, hazardous things taking place.” He acknowledged that as president it was his responsibility to deal with all these problems. “People are saying, ‘You’re the most powerful person in the world. Why aren’t you doing something about it?’”

The power of the presidency has two sides. On one, it is an extraordinary concentration of constitutional and legal authority. On the other, as Obama said, it can be limited and dubious.

Soon, Trump will experience both the power and its limits.