When Steve was hosting a show on NPR this week, several callers questioned whether the United States should be sending 3,000 troops and $500 million to help control the outbreak of the Ebola virus in West Africa.
It's true Washington is 4,669 miles from Monrovia, the capital of Liberia, where the epidemic is centered. It's also true the resources sent to Africa could be used here at home to improve the health of underserved Americans.
Still, President Obama made the right call. If anything, his response to the crisis has been too slow.
Defining where and when American interests are engaged in a foreign crisis is not always easy. Even the most hawkish voices on Capitol Hill don't think we can be "the world's policeman." Nor can we solve every humanitarian problem.
One of our motives in fighting Ebola is simply moral. With all its flaws, America is a good nation, a charitable nation, and when it comes to crises like Ebola, it is also -- in Madeleine Albright's phrase -- an "indispensable nation."
Only the U.S. has the ability to transport and maintain the 1,700-bed clinics the president is sending to Liberia. Or supply home health care kits to hundreds of thousands of households. Or train 500 health workers a week.
And that's what's needed. This epidemic is far more serious than any previous outbreak of the virus. It's moved from rural to urban areas and breached international borders.
America's interest in halting the epidemic goes far beyond morality. Ebola is already causing food shortages, paralyzing transportation networks and undermining economies. Chaos could spread. Governments could topple. And vast areas of Africa could plunge into lawlessness and become breeding grounds for terrorists.
Again, this is not a guess, a fantasy cooked up in Washington. This sort of breakdown has already happened in places like Somalia, Yemen and western Iraq. And bad guys who would threaten global security are already using them as safe havens.
Then there's the potential threat from the virus itself, which kills more than half the people it infects and has no medical cure. Officials insist that right now, Americans are in no danger, but two other things are true. First: Viruses don't stop at borders (nor do airplanes and their passengers). And second: They have the ability to change and mutate.
Ebola today can only be transmitted through bodily fluids, like blood and sweat, which makes it relatively easy to contain with the right knowledge. The nightmare is an airborne virus that can spread as easily as influenza.
There's a rough parallel here to the justification for battling the Islamic State in Iraq and Syria. Those brutal jihadists, like the Ebola virus, could destabilize our friends and allies and cause the sort of "breakdown" in civil order Obama's talking about.
One enemy carries bombs, and the other germs. But they are both mutations in their way: malign in their mission and hard to eradicate. And both threaten our vital national interests.
Steve and Cokie Roberts can be contacted by email at firstname.lastname@example.org.