Two events this week, half a globe apart, symbolize an important transformation in the focus of U.S. international relations.

In Berlin on Monday, former Soviet President Mikhail Gorbachev, the current leaders of Germany and other European nations, and Secretary of State Hillary Clinton celebrated the 20th anniversary of the destruction of the infamous Berlin Wall.

That courageous, spontaneous act not only demolished the very symbol of the 45-year Cold War between democratic and communist Europe but precipitated the events that led to reunification of Germany and, in a larger sense, the entire continent.

And though it was not fully evident at the time, it marked the beginning of the end of an era in which that East-West struggle — and particularly U.S. ties to Europe — dominated American foreign policy.

On Thursday, President Barack Obama left Washington for the Far East on a trip that features a visit to China, rapidly becoming the key U.S. relationship in an increasingly Asia-centric era. Though China remains the world’s most important communist government, its relationship with the U.S. has less of the ideological emphasis that was a key aspect of the U.S.-Soviet dynamic.

And though the relationship has strategic and military dimensions, it centers far more on such issues as trade, economic development and the environment.

The primacy of economic issues is underscored by the fact that Obama’s first stop in China on Sunday night is not Beijing, the capital and political center, but Shanghai, the leading commercial center and chief symbol of its economic development.

And though such traditional U.S.-Chinese issues as human rights will be discussed, the agenda centers heavily on economic-related issues, including efforts by both countries to spur global economic activity, the fallout from U.S. action imposing new tariffs on Chinese tire and steel exports, and recurring U.S. complaints that China has undervalued its currency.

Beyond the U.S.-China relationship, Obama’s trip is designed to demonstrate his interest in re-emphasizing U.S. relations with Asia and offset concerns that developed during the Bush years.

Meanwhile, the importance of the U.S.-Asia relationship is also illustrated by the fact that the most significant current U.S. military tests are also there, in the rugged region that includes Afghanistan and Pakistan.

To be sure, U.S. military engagement in Asia is nothing new. America fought two bloody wars there during the Cold War era, the 1950-53 Korean War and the lengthy, unsuccessful effort in the 1960s and 1970s to maintain an independent, democratic South Vietnam. But both were part of the effort by the U.S. and its Western European allies to contain the international communist movement centered in Moscow.

By contrast, the current, decade-long military campaign to subdue terrorists in Iraq, Afghanistan and Pakistan stemmed from the threat to the West of terrorist attacks unleashed from that region by the forces of Islamic fundamentalism, especially al-Qaida and its elusive leader, Osama bin Laden.

Despite this primary concern with events in Asia, the U.S. remains extensively engaged in Europe. But even one current military-related issue affecting U.S.-European relations — the Obama administration’s proposal to reconfigure a proposed missile defense system in Eastern Europe — is mainly directed at a potential threat from Iran.

By contrast, most U.S. military moves during the second half of the 20th century sought to protect Europe from the threat of attack from the Soviet Union. Russia remains a nuclear power, but the likelihood of any real threat from the successor to the Soviet super-state ended even before the fall of the Berlin Wall.

And the major foreign policy dilemmas facing Obama Afghanistan, Pakistan, Iran, North Korea and the Israeli-Palestinian relationship are all centered in Asia.