WASHINGTON — The number of U.S. drug overdose deaths has begun to level off after years of relentless increases driven by the opioid epidemic, Health Secretary Alex Azar said Tuesday, cautioning that it's too soon to declare victory.

"We are so far from the end of the epidemic, but we are perhaps at the end of the beginning," Azar said in remarks prepared for a health care event in Washington sponsored by the Milken Institute think tank.

Earlier this month, the CDC released figures that appear to show a slowdown in overdose deaths in late 2017 and the first three months of this year. Centers for Disease Control and Prevention

Confronting the opioid epidemic has been the rare issue uniting Republicans and Democrats in a politically divided nation. A bill providing major funding for treatment was passed under former President Barack Obama, and two more have followed under President Donald Trump.

More than 70,000 people died of drug overdoses last year, according to preliminary numbers released by the Centers for Disease Control and Prevention this summer— a 10 percent increase from 2016. Health and Human Services — the department Azar heads — is playing a central role in the government's response.

In his speech, Azar suggested that multipronged efforts to bring the epidemic under control are paying off. He ticked off statistics showing an increase in treatment with medications such as buprenorphine and naltrexone. There's solid evidence backing medication-assisted treatment, when used alongside counseling and ongoing support. He also noted that there is much broader access to the overdose-reversing drug naloxone, and a documented decline in the number of people misusing prescription opioids.

Azar said that toward the end of last year and through the beginning of this year, the number of deaths "has begun to plateau." Azar was not indicating that deaths are going down, but noting that they appear to be rising at a slower rate than previously seen.

Earlier this month, the CDC released figures — also preliminary — that appear to show a slowdown in overdose deaths in late 2017 and the first three months of this year. From December to March, those figures show that the pace of the increase over the previous 12 months has slowed from 10 percent to 3 percent, according to the preliminary CDC figures.

Despite the slowdown, the nation is still in the midst of the deadliest drug overdose epidemic in its history. Opioids were involved in most of the deaths, killing nearly 48,000 people last year.

While prescription opioid and heroin deaths appear to be leveling off, deaths involving fentanyl, cocaine and methamphetamines are on the rise. Fentanyl is a synthetic opioid much more powerful than heroin, used as an additive in street drugs.

During Obama's last year in office, his administration secured a commitment to expand treatment and Congress provided $1 billion in grants to states. Trump declared the opioid epidemic a national emergency. Two major funding bills have passed under his watch. While Trump got headlines with his call for using the death penalty against major drug dealers, his administration has built on the treatment approach that Obama favored.

The Medicaid expansion in Obama's Affordable Care Act has also played a critical role, paying for low-income adults to go into treatment. A recent Associated Press analysis showed that states that expanded Medicaid are spending their new opioid grant money from Congress more judiciously, going beyond basics like treatment for people in crisis. Trump tried to repeal the Medicaid expansion, but failed.

Advocates for those struggling with addiction are pleased to see that more and more it's considered a disease and not a sign of moral weakness. But they say the U.S. has a long way to go build what they call "an infrastructure of care," a system that incorporates prevention, treatment and recovery.

In an interview with The Associated Press this summer, a CDC expert said the overdose death numbers appear to be shifting for the better, but it's too soon to draw firm conclusions.

Month-to-month data show a leveling off in the number of deaths, said Bob Anderson, a senior statistician with the National Center for Health Statistics. However, those numbers are considered preliminary, since death investigations have not been completed in all cases.

"It appears at this point that we may have reached a peak and we may start to see a decline," said Anderson. "This reminds me of what we saw with HIV in the '90s."

Final numbers for 2018 won't be available until the end of next year and things could also get worse, not better.