Donald Trump has made a lot of promises, but as president, there's only so much he can do alone. That said, some of the things he could do as president would have a significant and immediate impact.

Bruce Ackerman, a professor of law and political science at Yale, told ATTN: that presidents have gained power over the past few decades by staffing the White House Counsel's Office and the Office of Legal Counsel in the Justice Department with lawyers who are able to find "creative interpretations" of laws to help the president accomplish their goals.

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"If Trump wants to do something that seems to be inconsistent with serious readings of statutes, there may be a creative reinterpretation of the statute," Ackerman said.

"Any program that is already in existence, the president has a lot of power to change the rules, change the regulations, adjust how programs are administered," Julian Zelizer, a professor of history and public affairs at Princeton University told ATTN:. "We've seen President Obama try to do this with immigration, with climate change. President Bush did this with national security and counterterrorism."

Through executive orders and executive actions, Trump could very well alter the government in serious ways. We decided to look at some of the scarier things Trump could do on his first day in office or shortly after.

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1. Drop a Nuclear Bomb

Americans were rightfully unsettled when rumors emerged that Trump had shown interest in using nuclear weapons. Senior military officials have indicated it would not be difficult for Trump to use such weapons.

"The constraints on nuclear weapons are mostly those of history, by which I mean, people have understood ever since World War II what the horrors are of using nuclear weapons, and nobody's done it since," Harold Bruff, a law professor at the University of Colorado, Boulder, told ATTN:. "The one thing I think that might stop him is military orders have to be executed by, of course, the various generals and admirals and so on. It might be that an order would be refused. That's a bad insurance policy, is what I would say."

While it seems unlikely Trump would initiate a nuclear strike right after taking office, it's within the realm of possibility.

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2. Roll Back Environmental Protections

Obama has used his executive power to attempt to confront climate change in many ways. From the Paris climate agreement to his executive orders that were meant to work against climate change, he's done a decent amount. That said, Donald Trump could quickly reverse that progress after taking office.

"He could start to weaken the enforcement of EPA rules and regulations on the environment, and he could either make it clear he doesn't want the EPA to be enforcing things aggressively or he could staff the EPA ... with officials who would support his agenda," Zelizer said. Executive orders of past presidents can be reversed by a new president, so Trump could easily nullify many things Obama has done.

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3. Roll Back Abortion Rights

There have been many executive orders related to abortion rights, which a President Trump could undo. "He can cut back on various kinds of abortion-related executive orders that have been out there for many administrations," Bruff said.

For example, Obama used his executive power to remove a policy that blocked funding to international health groups that perform abortions.

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4. Go After Immigrants

It's no secret that Trump is not a fan of illegal immigration, and as president, he could do a lot to go after undocumented people. "With immigration, he could staff [the INS] with officials who would be very aggressive," Zelizer said. Obama has also initiated executive orders that would protect immigrants, and Trump could reverse them.

Obama's 2014 executive order on immigration expanded certain protections from deportation to undocumented parents of U.S. citizens who have lived in the country for more than five years. It also expanded the Deferred Action for Childhood Arrivals program, so that undocumented immigrants who have been in the country since at least 2010 could apply for deportation deferral.

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5. Roll Back Gun Control

Earlier this year, Obama directed the Bureau of Alcohol, Tobacco and Firearms to more strictly enforce standing laws that require gun sellers to be licensed and to conduct background checks on their buyers. Donald Trump has supported the NRA and spoken at length about the need to expand gun access, so it seems likely he'd tighten the throttle on those regulations.

All of that said, if Trump tried to take his executive power too far, there is something that can be done. "If he pushes executive power too far and is doing it in unconstitutional ways, in illegal ways, Congress reserves the right to impeach," Zelizer said.