There's always some dictator, it seems, who needs persuading that he should release political prisoners, or curb human rights, or step down from office.
U.S. officials are constantly being described as "applying pressure" to these foreign leaders. But if they're not threatening war or serious sanctions, what sort of pressure can diplomats apply?
"The word 'pressure' is very often used by the press to describe a process that is much more subtle and, in effect, represents appeals to another country's best interests," says John Campbell, a former U.S. ambassador to Nigeria.
U.S. officials seeking to convince allies and enemies to do things their way are engaged in a constant juggling act of lesser threats, small promises and peer pressure.
Not Wielding Big Sticks
Sometimes, diplomats are blunt. In 1973, the U.S. wanted to resupply Israeli forces during their war with Arab nations including Egypt and Syria. European allies refused to let the U.S. air force fly over their territory or use their bases for refueling stops.
That is, until Secretary of State Henry Kissinger sent a scathing telegram to the Portuguese prime minister, over President Richard M. Nixon's signature, which "threatened to leave Portugal to its fate in a hostile world," as Kissinger put it. Portugal subsequently allowed the U.S. use of Lajes Field in the Azores.
There have been other occasions when senior diplomats got their way by warning foreign leaders that, unless they got with the program, a rain of U.S. bombs was about to fall on them. But such occasions are rare, diplomats say.
"If you're asking someone to do something that's contrary to their political survival, pressure isn't going to mean a whole lot," says Ronald Neumann, president of the American Academy of Diplomacy and a former ambassador to Afghanistan, Algeria and Bahrain.
Instead, it's more like convincing your child to do homework, says James Dobbins, a former assistant secretary of state. You start out by urging, get allies to help you convince the nation of the necessity of this step, offer inducements and, at some point, threaten sanctions.
Often, it's a combination of all these things.
"It usually consists of arguments explaining why it's in the country's interests to do something — and why it's not in its interests not to do something," says Dobbins, now the director of RAND's International Security and Defense Policy Center.
U.S. diplomatic staff may offer other countries help with implementing textile quotas or visa restrictions against the nation in question.
"The other way is to isolate a country is by not dealing with it, or encouraging other countries not to deal with it," says Daniel Hamilton, another former State Department official who is now at the Johns Hopkins School of Advanced International Studies.
Much of the time, there is no apparent quid pro quo.
It's simply "understood" that going along will make for a happier relationship down the road, says Jeswald Salacuse, a professor at the Fletcher School of Law and Diplomacy at Tufts University.
Requests Made of U.S.
Most countries seek favors in similar ways, but the U.S. operates under certain limitations.
"There are things we can't do in secret, like giving money to people," says Thomas Carothers, vice president for studies at the Carnegie Endowment for International Peace. "That's just not how our government operates."
Any significant promise or threat has to be run up the chain of command at the State Department. Other departments may get involved, too, such as Defense and the Office of the U.S. Trade Representative. If a matter is sensitive enough, it will be vetted by the National Security Council. And if serious dollars or policy changes are involved, the executive branch will have to convince Congress to get on board.
"There are probably 200 telegrams a day leaving the State Department that are doing this in some regard," Dobbins says. "A particular crisis, such as Libya, can lead to hundreds and even thousands of requests."
Perhaps that's why it matters so much who makes the offer or request. If the U.S. secretary of state gets on the line, or the president himself, the other country knows it's important.
"You're demonstrating that something is really important to the United States by the level of the person making the call," says Neumann, the American Academy president. "If your second cousin calls you, that's one form of pressure. If your mother calls, that's a different kind of pressure."
On a more specific level, another tool diplomats have at their disposal is the threat that the president will make a disparaging reference about a country's policies in a speech if its leaders don't play a little ball.
Conversely, the promise of a visit to the White House, for example, is a coveted gift to bestow. Even a few minutes alone with the president might be enough to help solve some problem that's been nagging at another country's leader for a long time.
"Access is not just ceremonial," says Carothers, the Carnegie Endowment scholar. "Bureaucracy moves if the president gives orders."
Weight Of U.S. Good Graces
Getting in the president's good graces matters because the U.S. still holds considerable sway in the world. Despite a lot of contemporary hand-wringing about America's relative decline, the U.S. is able to extend its interests into more parts of the world than any other power.
"We are still the biggest economy in the world, and being friends with our economy is really helpful to a lot of countries," says Cartothers.
U.S. diplomats don't always know exactly how far they can push friends and adversaries, Carothers suggests. They may have underestimated the extent to which they could influence ousted Egyptian President Hosni Mubarak, he says, while perhaps holding less sway than they think inside Russia.
Trying to find the right mix — and trying to get other countries to act in the U.S. interest — is an unending project.
"Diplomacy is all about getting other governments to do what you want them to do," says Dobbins, of RAND. "That's the whole reason we maintain a diplomatic establishment."