WASHINGTON (AP) -- President Barack Obama on Wednesday outlined his vision for American foreign policy in the 21st century, an era he expects will be rife with challenges that demand U.S. leadership.
Obama said the U.S. would not intervene in every crisis but must be prepared to act alone or with others when confronted with direct threats to U.S. interests or regional conflicts that risk spillover.
In doing so, the president repeated familiar refrains from his immediate White House predecessors - George H.W. Bush, Bill Clinton and George W. Bush. Each of them had to deal with the changing geopolitical balance that has defined the world since the collapse of the Soviet Union in 1991.
A look at how the three previous U.S. commanders in chief approached foreign policy with diplomacy and military intervention:
-George H.W. Bush: The last World War II veteran to serve as president, Bush took office in 1989 as the Soviet Union began to crumble with the fall of the Berlin Wall. That forced a rethinking in what had been the driving foreign policy mission for four decades. Bush, a former CIA director and ambassador to China and the United Nations, took a far more internationalist approach than his predecessor, Ronald Reagan.
Bush launched military operations to oust leader Manuel Noriega from Panama, drive Iraq's Saddam Hussein from Kuwait and stabilize Somalia, an effort that did not succeed.
Bush made the most concerted push for Middle East peace since the 1970s by organizing the 1991 Madrid Conference with the crumbling Soviet Union. His administration grappled with the vacuum left by the dissolution of the Soviet Union, its impact on arms control and the end of its support for client states, which paved the way for eventual normalization of U.S. ties with Vietnam and Cambodia.
-Bill Clinton: Clinton inherited the disastrous Somalia mission and brought it to a swift end. A former Arkansas governor, Clinton focused largely on domestic issues at first and struggled with America's role in the world.
In 1994, he deployed U.S. troops to Haiti, but opted against intervention in the Rwandan genocide. He struggled over getting involved in the Balkans as Yugoslavia broke apart in the aftermath of the Cold War. In his second term he backed NATO airstrikes on Serbia over the Kosovo conflict while Russia protested, but took little action as Moscow wrestled to define its future.
Clinton oversaw the Northern Ireland peace agreement and immersed himself in efforts to forge deals between Israel and its Arab neighbors, succeeding with Jordan and coming arguably closer than any other American president with the Palestinians at Camp David in 2001.
He was also faced with the astonishing rise of China, which was emerging from isolation following the 1989 Tiananmen Square crackdown on pro-democracy protests, and sought Chinese help in dealing with North Korea's nuclear program. He was the first president to deal with the threat posed by Osama bin Laden and his al-Qaida network that launched attacks on the U.S. embassies in Kenya and Tanzania and on the USS Cole in a Yemeni port.
-George W. Bush: Bush's presidency was defined by the attacks of Sept. 11, 2001, that occurred nine months after his inauguration and the wars in Afghanistan and Iraq. The wars derailed the former Texas governor's plans to focus on Latin America.
The 9/11 attacks, followed by a surge in al-Qaida-related terrorism, spawned the war in Afghanistan and the global fight against terrorism, amid widespread sympathy for the United States.
Bush gathered a large coalition to attack the Taliban, which harbored Osama bin Laden in Afghanistan. But he was accused of using national grief and claims that Saddam had weapons of mass destruction as a reason to invade Iraq.
Accused of acting unilaterally during his first term, Bush signed off on multination diplomatic efforts to deal with nuclear threats posed by North Korea and Iran in his second four years in the White House. He also organized the most serious attempt to broker Israeli-Palestinian peace with process launched in Annapolis, Maryland, that lasted until Obama's election in 2008.
Bush's first foreign policy crisis was with China over its downing of a U.S. spy plane. A rising China coupled with complaints that the U.S. was ignoring Asia and increasing Russian assertiveness in former Soviet states, notably Georgia, also posed challenges for the 43rd president.