Faced with a Republican-controlled Congress that won’t do his bidding on Obamacare repeal, President Donald Trump has threatened to take the reins himself. As the president toys with the idea of cutting off billions of dollars in cost sharing reduction payments (CSRs) to health insurance companies, health care experts and lawmakers warn that this is just one of many ways the administration could trigger the “collapse” and “implosion” of the Affordable Care Act they routinely predict.

Some executive actions, like cutting off the CSRs, would be major, breaking news, but others could happen much more subtly, while still having a devastating effect on the insurance market and the millions of Americans who depend on it.

Here are some of the weapons in Trump’s health care sabotage arsenal.

1. Cutting Off CSRs

Two ways Trump could strike a fatal blow to the delicate Affordable Care Act exchanges involve cutting off the flow of cost sharing reduction payments to insurers, a move that would throw the insurance market into chaos and cause rates to skyrocket. His administration could wreak the same havoc by simply dropping the defense of an ongoing lawsuit by the House GOP on the legality of the payments that began under the Obama administration.

A couple of hardline conservative lawmakers on Capitol Hill are all for ending the payments.

On Tuesday, Sen. Ted Cruz (R-TX) blasted the payments as “corporate welfare” and told reporters their continued issuance would be “a mistake.”

Sen. Richard Shelby (R-AL), acknowledging the impact of cuts would be “draconian,” supports pulling the trigger as well. “The sooner it collapses the sooner we might get a bipartisan replacement,” he said.

But the vast majority of Republicans and Democrats on Capitol Hill have warned Trump not to tiptoe any closer to that particular cliff.

“I don’t think it would be very prudent for them to take actions to harm people here in our country, as if somehow or another that’s creating leverage,” added Sen. Bob Corker (R-TN), referencing Trump’s repeated boast that blowing up Obamacare’s exchanges would force Democrats to the negotiating table.

Sen. Lamar Alexander (R-TN), the chair of the committee that oversees health care, has officially asked the White House to continue the payments through the fall to give his members time to hold hearings and introduce legislation to stabilize the insurance market.

It’s unclear how the White House will respond.

2. (Not) getting the word out

If the Trump administration’s goal is to weaken the Affordable Care Act, inaction could be as just as damaging as action.

In the months leading up to the November-January open enrollment period, the Department of Health and Human Services (HHS) for the past several years has made a massive effort to get the word out to the public and encourage the uninsured to sign up for coverage.

Under the Obama administration, HHS bought ads on TV, Twitter and Facebook, partnered with corporations like YouTube and Uber to get the word out, and sent the president and his cabinet members around the country to stump for the program. Canceling or scaling back any one of these outreach efforts in the months ahead could significantly depress sign-ups.

During the final days of the last open enrollment period in January, for example, the recently installed Trump administration canceled already-paid-for TV and digital ads, depressing enrollment by hundreds of thousands of people compared to the previous year. More recently, the HHS redirected funding, that was supposed to be used on an ad campaign to encourage enrollment, to create an anti-Obamacare PR campaign.

3. Putting assistance on hold

Another area vulnerable to sabotage is the work HHS does assisting millions of people in signing up for a new health care plan or renewing their existing coverage—everything from keeping the Healthcare.gov website running to answering calls to sending out e-mail blasts reminding people to enroll.

Already the Trump administration has shut down centers in 18 major cities where people could get health care enrollment assistance and slashed in half the period of time people have to sign up.

Joshua Peck, the former chief marketing officer for Healthcare.gov, told TPM the closure of the call centers could seriously damage the market going forward. With fewer federal contract workers on hand to answer hundreds of thousands of calls, he said, wait times will increase and many people won’t enroll at all.

“The people who give up and drop off first are the really healthy people who don’t think they need health insurance,” he said. “But someone who is very sick and desperately needs health insurance will jump through every hoop, and wait as long as you allow them to. So we need to make it an easy process in order to get a population that reflects the country.”

4. Enforcing the mandate

Since taking office, the administration has been intentionally coy about its commitment to the ACA’s individual mandate. HHS Secretary Tom Price has refused to give Congress a direct answer as to whether it will enforce the tax penalty on people who go uninsured. Without the threat of that penalty, many younger and healthier people would choose to go without insurance, leaving behind a disproportionately older and sicker insurance pool with unaffordable costs.

Even pro-repeal Republicans like Corker have warned against killing or weakening the mandate. “People are working on bills to try to make health care work,” he said. “Anything the administration might do to counter that would be not productive.”

5. Waivers on steroids

The Affordable Care Act allows HHS to grant waivers to states to allow them to get around some of the law’s regulations as long as the coverage offered is “at least as comprehensive and affordable as would be provided absent the waiver.”

The Trump administration can take this waiver power and run with it, allowing states to implement a slew of policies that may decrease coverage and roll back benefits for millions of people. Work requirements for people on Medicaid, scrapping the rule that insurers cover birth control, and drastically hiking premiums are just some of the many changes that could come about through such waivers.