Russian President Dmitry Medvedev chose the day after Barack Obama's election victory to brandish a threat of ballistic missiles. Venezuelan President Hugo Chavez said of the president-elect: "I hope he doesn't end up being one more imperialist."
As for Al-Qaida, it likened Barack Obama to a favored slave doing his master's bidding.
Obama's running mate, Joe Biden, predicted the new president would quickly be tested by a dangerous world. That test might come from anywhere, but attention has focused on North Korea, Iran, Russia and Venezuela, and the al-Qaida terror group.
Obama's Republican opponent, John McCain, called him too inexperienced to be president. So did Hillary Clinton, now his choice for secretary of state. Since his election, Obama has filled his national security team with centrists and relative hawks — a possible warning not to underestimate him.
"What Obama absolutely must prove early on in his administration is that he cannot be played for a patsy, that he has the strength ... and that he understands his no. 1 duty is as commander in chief and protector of the United States," said Robin Niblett, the director of Chatham House, the London-based think tank.
Niblett said Obama's approach to foreign policy is the right one, and that his willingness to talk to America's adversaries will actually make their lives harder.
"I think these leaders are worried about how America is going to play them," he said. "So far, they have become very comfortable being able to play a rather simplistic American foreign policy."
Already there are signs that some of America's most strident foes are not eager for a fight.
Plunging oil prices have slammed the economies of Russia, Venezuela and Iran; health issues surround Kim Jong Il, the reclusive leader of North Korea, and have forced the retirement of Cuba's Fidel Castro; Iran's Mahmoud Ahmadinejad is facing a stiff re-election fight in 2009 amid double-digit unemployment and 30 percent inflation.
Fyodor Lukyanov, editor of the Moscow-based Russia in Global Affairs Magazine, noted that Medvedev and his mentor — Prime Minister Vladimir Putin — quickly dropped their hard-line stance after threatening to place short-range missiles near Poland in response to the Bush Administration's backing of a missile defense shield.
Three weeks after Obama's victory, Medvedev talked to Obama by phone and said he was looking for "constructive, partnerlike relations" and that "The conversation I had with the president-elect allows me to expect a similar U.S. approach."
"The Kremlin has signaled readiness to tone down its rhetoric," Lukyanov said. "Apparently, they decided to try to improve ties."
Even America's toughest critics sounded a conciliatory note. Ahmadinejad sent Obama a congratulatory letter. Venezuela's President Hugo Chavez drew parallels to John F. Kennedy even as he welcomed Russian warships into the Caribbean for joint naval exercises.
In Cuba, Raul Castro said he was willing to meet the new president on neutral ground. His brother, Fidel, tempered expectations of a change in U.S. policy or a lifting of the decades-old embargo, but called Obama a "smart man."
North Korea's state-run media have refrained from their usual anti-American rhetoric. They haven't commented on Obama's pledge to sit down with adversaries, but analysts say it has gotten Pyongyang's attention.
"North Korea certainly has good feelings about Obama," said Kim Yong-hyun, a professor at Seoul's Dongguk University. "But does it mean that the North will stake everything on Obama and try to curry favor with him? No way."
Analysts say softened language goes only so far in improving relations. The International Atomic Energy Agency says Iran continues to enrich uranium and is about halfway to having enough for a nuclear bomb, and unless it backs down, relations with the U.S. are unlikely to improve.
Chavez's conflict with the U.S. has intensified since he accused the Bush administration of backing a failed 2002 coup against him. He now says he would be willing to consider a trip to Washington for talks with Obama, but also hopes Obama does not turn into "one more imperialist" and wants him "to honor his race."
One organization that clearly hasn't softened is imminent is al-Qaida, whose no. 2, Ayman al-Zawahri, slurred Obama as a "house Negro" who had betrayed his black heritage and his father's faith.
"You were born to a Muslim father, but you chose to stand in the ranks of the enemies of the Muslims, and pray the prayer of the Jews, although you claim to be Christian, in order to climb the rungs of leadership in America," his audiotaped message said.
Some analysts say the tape shows al-Qaida's desperation, having launched no attack on U.S. soil since 9/11, and having alienated some followers by killing so many Muslims in attacks elsewhere.
"Al-Zawahri may have crossed some lines here," he said. "To attack Obama with a racial epithet is taking an enormous risk. You risk alienating those you are trying to reach."