One month into the presidency of George W. Bush, two of the world's largest alliances face a test of strength. One, across the Atlantic, is between the United States and European nations. The other, spanning the Pacific, binds Japan and the U.S. Signs of tension have been appearing in these vital alliances at the very time that President Bush is giving them top diplomatic priority.

What is straining Japan-U.S. ties is the recent collision of a U.S. nuclear-powered submarine with a Japanese fisheries training vessel. Inflaming public sentiment, moreover, are two incidents in Okinawa: the contempt expressed for local officials by a U.S. military commander, who called them "nuts and wimps" in an e-mail to subordinates, and an arson case involving a U.S. Marine. Unless the two nations deal properly with these issues, many Japanese will begin to doubt the value of the alliance itself.

The Atlantic alliance has shown signs of stress over the European Union's decision to build a rapid-reaction force and U.S. plans to build a national missile defense system. In a bid to bolster the alliance, British Prime Minister Tony Blair visited the U.S. over the weekend. It was Mr. Bush's first summit with a key U.S. ally other than Canada and Mexico. Meanwhile, a Japan-U.S. summit hangs in the balance, given the volatile political situation here.