For a president who hasn't enjoyed many foreign policy successes lately, Barack Obama did pretty well on his just completed trip to Asia.
In Japan, he reiterated in no uncertain terms the American defense commitment, including on the Senkaku islands in the East China Sea, which China also claims and calls the Diaoyus.
"Historically, they have been administered by Japan, and we do not believe they should be subject to change unilaterally," Obama said. "What is a consistent part of the alliance is that the treaty covers all territories administered by Japan."
In the Philippines, Obama signed a new agreement giving the United States expanded access to naval and air bases there for 10 years. This represents real progress and comes on top of U.S. agreements for troops to rotate through Australia and Singapore.
It's also a rebound to traditional U.S. policy. After a typhoon and volcanic eruption smashed the Subic Bay naval base in 1991, the Philippine government pressed for and the U.S. agreed to American withdrawal from a nation fronting the South China Sea, where much of the world's trade -- and oil -- passes.
China's naval buildup, its declaration last December of an expanded air defense identification zone in the East China Sea and its continued aggressiveness in the Spratly Islands raises the chance -- ominous in this centennial year of the outbreak of World War I -- of an armed clash with U.S. allies in the region.
Open warfare in this region could be disastrous, with enormous potential destruction of human life and physical infrastructure. For a sense of the terrible potential, read British historian Rana Mitter's recent book "China's War With Japan 1937-1945."
Obama's declarations in Japan and the Philippines and in his visits to South Korea and Malaysia will, one hopes, deter Chinese leaders from aggression that could lead to war.
On not all issues, however, was Obama so successful. In all four countries he touted the benefits of the Trans-Pacific Partnership trade agreement currently being negotiated.
Unfortunately, the December 2013 deadline for agreement on its terms has already gone by. One reason is what Obama has done -- or, rather, hasn't done -- in Washington.
And that is to get Congress to pass "fast-track" trade promotion authority allowing the president to negotiate trade agreements that Congress could approve or reject but not amend. If the president doesn't have trade promotion authority, other nations are reluctant to make concessions, lest Congress demand more in return for ratification.