Three days after his election to a second term, President Clinton opened the door Friday to an extended deployment of U.S. troops in Bosnia, a step he carefully avoided throughout his re-election campaign.

When U.S. troops arrived in Bosnia last December to uphold the peace agreement reached a year ago outside Dayton, Ohio, by setting up buffers between the warring Muslims, Croats and Bosnian Serbs, Clinton and his aides said the deployment would last a year. They said later some forces would remain until March, 1997, to conduct an efficient, phased withdrawal.

Now, he said, NATO, in which the United States plays a leading role, is considering whether to recommend to its participants a more limited, but extended, operation.