WASHINGTON — It’s no secret that smoking causes lung cancer. But what about diabetes, rheumatoid arthritis, erectile dysfunction? Fifty years into the war on smoking, scientists still are adding diseases to the long list of cigarettes’ harms — even as the government struggles to get more people to kick the habit.

A new report from the U.S. Surgeon General’s office says the nation is at a crossroads, celebrating decades of progress against the chief preventable killer but not yet poised to finish the job.

“The real emphasis needs to be put on the fact that we still have a major and tragic catastrophe going on,” said acting Surgeon General Boris Lushniak.

The report is being released Friday at a ceremony at the White House, after a week of headlines marking the 50th anniversary of the landmark 1964 surgeon general’s report that launched the anti-smoking movement. Far fewer Americans smoke today — about 18 percent of adults, down from more than 42 percent in 1964.

But the government may not meet its goal of dropping that rate to 12 percent by 2020, the new report cautioned.