A WORLD OF CHALLENGES AWAITS THE PRESIDENT By Jay Solomon

President Barack Obama’s reelection will provide him with little time to celebrate in the face of an array of global problems that include challenges posed by Iran’s nuclear program and widening political instability in the Middle East, which is fueling sectarian conflict and chaos from Syria to North Africa.

Behind these front-burner problems, Mr. Obama in his second term likely will have to refine U.S. policies toward China, in light of its growing economic might and military power in the Pacific.

The president is expected to face a renewed challenge from Beijing over continued U.S. arms sales to Taiwan, say administration officials and foreign-policy specialists. And many Asian officials fear that the dispute between Japan and China over an atoll in the East China Sea could escalate further, forcing Washington — Tokyo’s treaty ally — into a larger role.

The Obama administration over the past year has been touting its intention to tilt Washington’s strategic focus away from the Middle East and toward Asia, due to the region’s economic growth and China’s increasing power. And Republican challenger Mitt Romney had campaigned on expanding U.S. Navy capabilities to contain China.

But few regional analysts believe Mr. Obama will be able to significantly shift U.S. focus away from the Mideast over the next four years. Just weeks after his re-election, for example, he must decide whether to approve U.S. participation in a fourth round of negotiations this year with Iran over its nuclear program.

Israeli officials now say that military action could be needed by next summer to prevent Iran from reaching the capability for making atomic weapons. Iran insists its nuclear program is purely for civilian purposes.

The impact of Western sanctions has increased, contributing to a 40% fall recently in the value of Iran’s currency, the rial. That pressure is raising expectations that Tehran might be forced to compromise.

“On Iran, there does seem to be some traction toward a new direction,” said Rob Malley, who oversees Mideast issues for the International Crisis Group, a global analysis and advocacy organization.

But the White House will need to decide if Iranian concessions will satisfy Israel and the U.S.’s Arab allies, as well as pro-Israel lawmakers on Capitol Hill.

Elsewhere, pressure on the U.S. is mounting to support international military action in Syria and Mali.

In Syria, sectarian conflict has intensified, with human rights groups reporting nearly 40,000 killed over the past 18 months. Arab officials fear that the conflict is more rapidly spilling across borders, risking unrest in Lebanon, Jordan, Iraq and Turkey.

During the campaign, Messrs. Obama and Romney both campaigned against directly sending U.S. troops into Syria. But the Republican candidate said he would ensure that more arms reach rebels fighting President Bashar al-Assad’s rule, while Mr. Obama said he supports more nonlethal assistance.

In North Africa, the U.S. and Europe are supporting African-led military action in Mali, where al Qaeda and other extremist groups have secured safe-havens this year.

The Obama administration has been forced to more aggressively intervene in the conflict following the September attack on the U.S. consulate in Benghazi, Libya. U.S. intelligence officials believe members of al Qaeda in the Islamic Maghreb, the extremist group’s North African affiliate, may have helped plan the attack, which killed four Americans, including Ambassador Christopher Stevens.

A wild card for Mr. Obama’s second term will be the Arab-Israeli conflict, said Mideast analysts.

Peace talks between Israel and the Palestinians have been frozen for nearly two years, following Mr. Obama’s aggressive early initiatives aimed at forging an agreement.

Palestinian President Mahmoud Abbas has refused to return to talks until Israeli Prime Minister Benjamin Netanyahu freezes all Jewish construction in disputed areas. The Israeli leader, objecting to that demand, has said the Palestinians are seeking to set preconditions for any talks.

In recent weeks, however, Mr. Abbas has said he would seek a vote at the United Nations General Assembly that would recognize Palestine as an independent state. A positive vote would have limited legal effect, as only the U.N. Security Council can grant such status. But Mr. Abbas’ initiative could rekindle regional tensions, Mideast analysts said, and potentially lead to the U.S. Congress cutting aid for the Palestinian Authority.

“You could see things going to the point that the P.A. becomes an organization in name only,” said Mr. Malley of the International Crisis Group. “The whole Palestinian identity question will come back to the fore.”

Mr. Obama also will come under pressure to more directly engage Latin America, with Mexico and Brazil emerging as among the most important U.S. trading partners. The threats posed to U.S. borders by narco-trafficking gangs in Mexico could eclipse those posed by Mideast-based terrorist groups, national-security experts believe.

“Mexico is arguably the most important relationship the U.S. has,” said Michael Shifter, president of the Inter-American Dialogue. “It’s a little hard to explain how it’s been nearly absent from the campaign.”