Much of the news coverage of Ms. Clinton’s appearances before Senate and House committees focused on her jousting with Republicans over responsibility for the attack on a U.S. diplomatic outpost in Benghazi, Libya. But we were struck by the forcefulness and clarity with which she made the case that the United States faces a “very serious, ongoing” and “strategic” threat in North Africa from al-Qaeda affiliates and other jihadists — one that she argued demands a vigorous and comprehensive response.

“We are in for a struggle,” Ms. Clinton said. “But it is a necessary struggle. We cannot permit northern Mali to become a safe haven. . . . We’ve got to have a better strategy.”

The outgoing secretary’s statements were particularly striking when compared with President Obama’s inaugural address Monday, which promised to end “a decade of war” in favor of nation-building at home, and with the White House’s current approach to Mali. France sent troops there this month to prevent jihadists linked to al-Qaeda who are entrenched in Mali’s northern deserts from taking over the rest of the country.

But as the Wall Street Journal reported Thursday, Mr. Obama and his advisers have taken a skeptical view of the need for U.S. involvement. French requests for air refueling and surveillance help are still on ice two weeks after being made; the administration grudgingly agreed to transport some French troops to the country but only after trying to stick Paris with the bill. The Journal reported that while the Pentagon has wanted to target the leaders of al-Qaeda in the Islamic Maghreb (AQIM), which was involved in the Benghazi attack as well as last week’s assault on a gas field in Algeria, White House policymakers argue that the group doesn’t pose a direct threat to the United States.

Ms. Clinton evidently doesn’t agree. “People say to me all the time, well, AQIM hasn’t attacked the United States,” she said. “Well, before 9/11, 2001, we hadn’t been attacked on our homeland since, I guess, the War of 1812 and Pearl Harbor. So you can’t say, well, because they haven’t done something they are not going to do it.”

Ms. Clinton offered Somalia as an example of an effective U.S. response to such a threat. Over a period of several years, U.S. military forces carried out drone strikes and raids against al-Qaeda leaders and trained local forces, while diplomats patiently worked to foster a new and more representative Somali government.

“It took time,” Ms. Clinton said. “There were no shortcuts. But we had literally the boots of our American soldiers and the boots of American diplomats on the ground.”

The outgoing secretary’s point about U.S. leadership — and the results of its absence — doesn’t apply just to Mali. It is equally true of Syria, Afghanistan, Iraq and other “unstable environments.” If Mr. Obama continues to eschew an active U.S. role in those places, or to retreat from one, there will be, as Ms. Clinton said, “consequences.”