AS PRESIDENT Obama looks ahead, 2015 may be the most challenging and consequential year of his presidency on foreign policy. Here are some major global tests where he will need to marshal American diplomatic strength, leadership, and effectiveness this year.

Contain North Korea: Obama needs to box in the world’s most dangerous and unpredictable leader, Kim Jong Un. Obama was right to call out Sony for initially cancelling the Christmas release of “The Interview” after cyber-attacks. He can turn the tables on Pyongyang by designating it a state sponsor of terrorism, impose new financial sanctions, and enlist China’s help in restraining the North from threatening US allies South Korea and Japan.

Seal the two big trade deals:
The White House is signaling Obama’s desire to work with Republicans to conclude major free trade deals — the Trans Pacific Partnership in Asia and Trans Atlantic Trade and Investment Partnership with the European Union. Both would boost US economic growth and reclaim our global leadership on trade. Republicans will be with him. Obama’s problem will be to corral free-trade-averse Democrats, especially in the awakening liberal wing led by Senator Elizabeth Warren, to make this bid for free trade.

Pursue a nuclear deal with Iran: Obama and European leaders have been more than patient in negotiating with Iran’s divided leadership on its outlaw nuclear program. Conventional wisdom in Washington is that Tehran will likely not agree to the only deal the United States should consider — leaving Iran well short of a nuclear weapon with a heavily monitored and limited civil nuclear program. But falling oil prices and Secretary of State John Kerry’s aggressive diplomacy will give Obama one more chance this spring to convince Tehran to say yes rather than face even tougher sanctions in the future.

Squeeze Putin: Collapsing oil prices, a shaky ruble, and diminishing investor confidence have the Russian economy reeling. If Russian President Vladimir Putin won’t withdraw his forces from Eastern Ukraine, Obama should convince hesitant European leaders to increase the pressure by ratcheting up sanctions. Obama should also ensure NATO continues air patrols and troop reinforcements to shield allies Estonia, Latvia, and Poland from Putin’s intimidation.

Step up on Syria: A wavering Obama needs a more resolute and ambitious Syria strategy. He should launch a more ambitious program to arm moderate rebels to squeeze ISIS in its home base. The United States should also convince Russia, China, and the Arab world to launch a vastly expanded humanitarian relief effort to help Syria’s 11 million-plus homeless.

Commit to a climate agreement: Obama is positioning the United States to lead on global climate change talks after two decades after two decades of American lassitude. His bold EPA decision on coal, joint agreement with China’s Xi Jinping, and Kerry’s active diplomacy are pushing countries closer to the first global deal in Paris by the end of the year. Climate could end up as his most important foreign policy legacy.

Rebuild Brand America: Many Americans may not realize just how much our major asset — the trust others have in us — has taken a major hit overseas. Deepening racial divisions at home as well as torture and surveillance revelations have made even our closest friends abroad question US credibility as the world’s guardian of democratic values and human rights. A renewed campaign to rebuild America’s image in Germany, India, Brazil, and other leading countries plays to an Obama strength — he is still an admired figure in much of the world.

This year will indeed be a time of testing for Obama. Some overseas question his commitment to sustain America’s traditional global leadership role. Others believe the Democratic Party’s defeat in the midterm elections have reduced his power at home. But Obama still commands the world’s most powerful military and diplomatic corps on the global stage — 2015 gives him a chance to prove the critics wrong.