In the Georgian Black Sea port of Batumi, the first American naval vessel arrived Sunday to distribute American humanitarian aid.

A train carrying oil cars exploded while traveling near Gori, the city in central Georgia that Russia had occupied for about 10 days. Georgian officials said the train had struck a mine left behind by Russian troops. No one was reported killed in the blast or the raging fire that followed, which sent thick plumes of black smoke across the countryside.

With the bulk of Russian troops now withdrawn to the enclaves or to Russian soil, Mr. Saakashvili described the war against South Ossetia and Russia  a military defeat that imperiled his government and threatens Georgia’s fragile economy  as a seminal moment that offered the seeds of political and national success.

In an interview in his office that stretched until nearly 2 a.m., Mr. Saakashvili said that Georgia had gained allies in the world and would embark upon a campaign of rebuilding.

He predicted continued American support and said that he spoke by phone with the presumptive Republican nominee for president, Senator John McCain, as often as twice a day, and that he was in regular contact with Senator Joseph R. Biden Jr., who has been picked to run for vice president on the Democratic ticket.

He also said that the Bush administration had not communicated disappointment or signaled a decline in its support for him since he gave the order on Aug. 7 to attack Tskhinvali, the South Ossetian capital.

He said that while he might face pressures in the months ahead, as the effects of the war ripple through the economy, he said he expected to weather any troubles. “There has been tremendous solidarity,” he said.