Senator Obama’s early opposition to the war in Iraq is the best known of his views, but voters taking his measure as a potential president will discover that he is a leader in securing stray weapons from the former Soviet Union, a key backer of American aid to the Congo, and that he would tend to support a missile strike on Iran if other methods fail to get Tehran to abandon its nuclear program.

In most respects, the Illinois Democrat’s positions on foreign affairs are more fleshed out than one might expect for a leader concluding his second year in the Senate, though they lack the breadth and detail set forth by some of his colleagues who have spent decades in the public eye.

When he took office in 2005,Mr. Obama became the most junior Democrat on the Senate Foreign Relations Committee. However, the issues section of his Senate Web site, which lists his views on crime and aid to senior citizens, gives few details of his thoughts on America’s role abroad.

Mr. Obama’s foreign policy positions, gleaned from his speeches and writings, are squarely in the Democratic Party mainstream, though he often goes out of his way to distance himself from some on the left who downplay the dangers facing America. His statements and associations in foreign policy circles also suggest he might, as president, be more willing to use force to intervene in humanitarian crises than other presidents have. It seems certain he would make promotion of human rights a more serious factor in American diplomacy. He would also be likely to impose stricter rules on CIA interrogators — rules that some argue could hamper intelligence gathering and ultimately cost American lives.

In his new, best-selling book, “The Audacity of Hope,” Mr. Obama devotes a 53-page chapter to international issues. In one passage, he scolds self-described liberals for saying in a poll last year that their top foreign policy concerns were “withdrawing troops from Iraq, stopping the spread of AIDS, and working more closely with our allies.”

“The objectives favored by liberals have merit. But they hardly constitute a coherent national security policy,” Mr. Obama declares. Alluding to the Vietnam War, he says, “It’s useful to remind ourselves, then, that Osama bin Laden is not Ho Chi Minh, and that the threats facing the United States are real, multiple, and potentially devastating.”

On Iraq, Mr. Obama has been calling for more than a year for a “phased redeployment” of American troops. He also favors a conference of regional powers, including Iran and Syria, to discuss Iraq’s future. He has shied away from rigid deadlines and has even spoken of keeping American troops in Iraq if Iraqis can settle their differences. “He’s been very thoughtful and judicious about what our stakes are in the conflict,” a State Department and National Security Council official under President Clinton, Susan Rice, said. “He basically presaged the Iraq Study Group’s comments.”

Mr. Obama has also taken pains to make clear that he is not a pacifist. “I am not opposed to all wars. I’m opposed to dumb wars,” he said at an anti-war rally in 2002. “What I am opposed to is the cynical attempt by Richard Perle and Paul Wolfowitz and other armchair, weekend warriors in this administration to shove their own ideological agendas down our throats, irrespective of the costs in lives lost and in hardships borne.”

Like other Democrats, Mr. Obama has faulted the Bush administration for not pushing harder for peace between Israel and the Palestinian Arabs. The senator has also been publicly supportive of Israel and enjoys significant support in the Jewish community in Illinois. “He has long-standing position papers going back early into his Senate campaign which have been very strong on the defense of a safe and secure Israel,” a Chicago lawyer who traveled with Mr. Obama in Israel in January, Alan Solow, said.

An Israeli newspaper, Ha’aretz, has been asking Israeli opinion leaders each month to score possible American presidential hopefuls. Mr. Obama tends to score at or near the bottom. The paper’s chief Washington correspondent, Shmuel Rosner, said that’s in part due to Mr. Obama’s novelty on the political scene, but also to other factors. “His supporters will come mainly from the left wing of the Democratic Party and from the African-American community — from constituencies which are traditionally not that supportive of Israel,” the journalist said.

Mr. Solow, who leads a national association of Jewish community centers, dismisses talk that Mr. Obama might waver on Israel. “There isn’t anything he has said or done that would give me concern about his holding high office,” the Jewish leader said. Asked if he would support the senator for president, Mr. Solow said, “Oh, absolutely.”

During the fighting between Israel and Lebanon earlier this year, Mr. Obama co-sponsored a resolution endorsing Israel’s right to self-defense and condemning Hamas and Hezbollah. He also co-sponsored the Palestinian Anti-Terrorism Act of 2006, discouraging international aid to Hamas or contacts with it unless Hamas recognizes Israel, disarms, and renounces violence.

Mr. Obama favors direct discussions between America and two states President Bush named as parts of the axis of evil, Iran and North Korea. “We have not explored any kind of dialogue with either Iran or North Korea, and I think that has been a mistake. As a consequence, we have almost no leverage over them,” the senator told NBC in October.

As a Senate candidate in 2004, Mr. Obama said he would support military action against Iran if diplomacy fails to rein in the mullahs’ nuclear program.

“In light of the fact that we’re now in Iraq, with all the problems in terms of perceptions about America that have been created, us launching some missile strikes into Iran is not the optimal position for us to be in,” he told the Chicago Tribune. “On the other hand, having a radical Muslim theocracy in possession of nuclear weapons is worse. So I guess my instinct would be to err on not having those weapons in the possession of the ruling clerics of Iran. … I hope it doesn’t get to that point.”

Mr. Obama also told the Tribune he would back American military action to secure Pakistan’s nuclear arsenal if President Musharraf is overthrown by radicals.

In his two years in the Senate, Mr. Obama has been a leading advocate for efforts to secure so-called loose nukes and other weapons in the former Soviet Union. “He’s rapidly become the heir to Sam Nunn, and Senator Lugar’s intellectual counterpart,” Ms. Rice said.

In 2005, Mr. Obama traveled to the region along with Mr. Lugar, the Indiana Republican who chairs the Foreign Relations Committee. Earlier this month, Congress passed a Lugar-Obama bill to expand efforts to destroy stockpiles of conventional weapons, such as shoulder-fired missiles. “It’s obviously more important than ever in the context of the war on terror,” Ms. Rice said.

While press reports about Mr. Obama’s trip to Africa in August focused on the rock-star treatment he received and on the public AIDS test he took, Ms. Rice noted that the senator parted company with other American leaders by publicly calling attention to rampant corruption that diminishes Africans’ standard of living.

“He went to the belly of the beast in Nairobi and called a spade a spade, which I thought was very brave and very badly needed,” she said.

Mr. Obama has been vocal in pushing for more action by America and other nations to stop the genocide in the Darfur region of Sudan, but he has also drawn attention to a less noticed but even bloodier conflict, the long-running war in the Congo. A bill Mr. Obama sponsored to provide $104 million to encourage democracy and stability in the war-torn country quietly passed Congress earlier this month and is awaiting Mr. Bush’s signature.

Key advisers in Mr. Obama’s foreign policy orbit include Ms. Rice; a Pulitzer Prize-winning anti-genocide activist, Samantha Power; a national security adviser to Mr. Clinton, Anthony Lake, and Senator Obama’s foreign policy staffer, Mark Lippert.

Ms. Rice, who now works at the Brookings Institution, is unabashed about her views on a potential Obama presidency. “I think he’d be excellent,” she said.

However, Ms. Power, who took leave from Harvard’s Kennedy School last year to work in the senator’s office, may be the foreign policy specialist campaigning most publicly on Mr. Obama’s behalf. During a speech last month at Northwestern University, she spoke of what a “President Obama” might do and sowed doubts about two of his potential primary opponents, Senator Clinton and the Democratic nominee in 2004, Senator Kerry of Massachusetts.

“Hillary Clinton came out about two-and-a-half, three weeks ago and endorsed the president’s position on coercive interrogation techniques, not McCain’s position, distinguishing herself from McCain, perhaps with 2008 in mind,” Ms. Power said. She also faulted Mr. Kerry for failing, during his debates with Mr. Bush, to mention the torture of prisoners at Abu Ghraib. A columnist for Time magazine, Joe Klein, has reported that Mr. Kerry made the decision based on focus groups his campaign conducted. “The answer came back, ‘It’s not a winner politically,'” Ms. Power said.

Spokesmen for Mrs. Clinton did not respond to requests for comment. A spokesman for Mr. Kerry, David Wade, said Mr. Kerry “has a 21-year record of leadership exposing human rights abuses and insisting on accountability.”

Ms. Power did not say specifically what Mr. Obama would do about interrogations, but implied he would be more responsive to human rights concerns, while still protecting America. “Just as you can’t leave values out of foreign policy or you end up to some degree in the mess we’re in, I believe, so too, you can’t leave security out of foreign policy,” she said, adding that “a kind of a middle course” would be “what I think President Obama will bring to the White House.”

During Ms. Power’s talk at Northwestern, she detailed the same poll results about liberals’ foreign policy goals that Mr. Obama mentions in his book. She went on, as he does, to critique those priorities as shortsighted.

Ms. Power has declared the notion of forcible humanitarian intervention “dead,” at least for now, thanks to the fallout from the Iraq war. “Certainly, I, in the Darfur context, would not even think about advocating a U.S. invasion,” she said at Northwestern. “The reality is jihadis would follow American troops.”

Ms. Power, who backed a former NATO commander, Wesley Clark, in the 2004 presidential contest, did not respond to calls and e-mails seeking comment for this article.

Mr. Lake, a professor at Georgetown, compares Mr. Obama to President Clinton.

“I worked on the campaign of President Clinton, then-Governor Clinton, in 1992. I haven’t seen anybody since with the same talent for being formidably intelligent and being able to place complicated concepts in such eloquent terms as Senator Obama has,” Mr. Lake said. “I think a candidate like Obama only comes along once in a while.”

Mr. Lake praised Mr. Obama for his conviction that America can be a moral leader abroad. “He believes America can be a positive force in world, but we have to be tough-minded about it,” Mr. Lake said.

In his book, Mr. Obama downplays the military threat posed by China. “Our most complex military challenge will not be staying ahead of China (just as our biggest challenge with China may well be economic rather than military),” he writes. “More likely, that challenge will involve putting boots on the ground in the ungoverned or hostile regions where terrorists thrive.”

Last month, Mr. Obama voted in favor of America’s nuclear deal with India, which passed easily, though 12 Democrats opposed it. As a rust belt senator close to labor interests, he stood with most Democrats in voting against the Central America Free Trade Agreement last year. However, earlier this year, Mr. Obama broke with some in his party to vote in favor of a free trade deal with Oman. Two potential presidential candidates, Senators Biden of Delaware and Dodd of Connecticut, voted against that pact, but Mrs. Clinton supported it.

Last year, Mr. Obama joined with all the Democrats on the Foreign Relations Committee in voting against the confirmation of John Bolton as America’s ambassador to the United Nations. The Illinois senator also voted twice to prevent the full Senate from taking up Mr. Bolton’s nomination.

In September, Mr. Obama and most of his Democratic colleagues voted against a bill establishing military commissions and in favor of an amendment to permit detainees suspected of terrorism to file habeas corpus challenges in federal court. The bill passed without the amendment, but the issue is likely to be revisited next year.

Republicans are struggling to craft a coherent critique of Mr. Obama. Writing on National Review’s Web site recently, an economist and commentator, Lawrence Kudlow, declared that the senator’s record firmly establishes him as “an extremely liberal-left politician.” Two days later, a former speechwriter for President Reagan, Peggy Noonan, published a column in the Wall Street Journal describing Mr. Obama as a cipher. She called the senator “the man from nowhere, of whom little is known.”

Mr. Obama was born in Hawaii to a Kenyan father and American mother. The future senator spent four of his grade school years in Indonesia and managed to pick up the language there.

Mr. Solow, who said he supported the Iraq war at the outset, said Mr. Obama’s opposition to it is a direct and forceful rebuttal to any suggestion he is too green to be commander in chief. “For all the criticism about his experience and lack of knowledge, he was the person who actually had it right,” Mr. Solow said.