WASHINGTON (AP) — President Barack Obama had a “pen and phone” strategy. President Donald Trump has an eraser.

Since his first days in office, Trump has set out on a wholesale reversal of a long list of accomplishments that Obama achieved through executive action.

The latest Obama-era policy to fall is the program shielding from deportation hundreds of thousands of young people brought into the country illegally as children. The Trump administration Tuesday said the government would stop issuing new work permits while lawmakers debate whether to pass another solution.

In explaining his decision, Trump accused Obama of making “an end-run around Congress” to protect the so-called “dreamers.” In effect, this time it’s Trump making an end-run around Obama.

Obama, coming out of semi-retirement, retorted that Trump’s action was a “cruel” and “self-defeating” decision tinged with politics.

It was yet another demonstration of the easy-come, easy-go nature of presidential achievements attained through unilateral action: What one president does by executive fiat, the next can just as quickly overturn.

And it’s not just a Trump-Obama dynamic. Trump’s executive orders will be subject to revision by his successor. And Obama didn’t hesitate to reverse the actions of his predecessor, George W. Bush.

For all of that, though, Trump has been “unusually aggressive in his use of unilateral powers,” says Kenneth Mayer, a University of Wisconsin-Madison political scientist and expert on presidential powers and executive orders.

While it’s hard to systematically rank presidents on their use of executive actions, Mayer says “there are examples of Trump going beyond what other presidents have done in terms of the frequency and nature of unilateral action.”

Trump, lacking any major legislative accomplishments despite the advantage of a Republican-controlled Congress, has issued dozens of executive orders and actions during the past seven months that have had a sweeping effect across the scope of government.

He’s pulling the United States out of the landmark Paris climate agreement through which nearly 200 countries had committed to combat global warming by reducing polluting emissions. He’s scrapped an Obama administration policy that let national parks ban the sale of bottled water to fight littering. His Education Department has lifted Obama-era guidance to schools to allow transgender students to use the bathroom of their choice. He tweeted out word that transgender individuals would no longer be allowed to serve openly in the military, as provided by the Obama administration, forcing the Pentagon to scramble to draft new rules.

Trump’s actions on environmental matters extend well beyond climate change: He’s moved to rip up Obama’s Clean Power Plan, regulations that sought to reduce emissions from coal-fired power plants. His executive order on regulatory reform has been cited by EPA Administrator Scott Pruitt as a reason to delay or roll back a raft of Obama-era environmental regulations, from cleaning up water pollution from coal mines to blunting limits on emissions of toxic mercury from power plant smokestacks.

There’s likely more to come: Trump’s Labor Department wants to undo an Obama administration rule extending mandatory overtime pay to 4.2 million more workers. And the administration is reviewing a potential rule that would let employers opt out of providing no-cost birth control to women for religious and moral reasons.