BOB ABERNETHY, anchor: The announcement this week by Advanced Cell Technology, a private biotech company, that it had cloned a human embryo has drawn strong reactions from political and religious leaders.

Pope John Paul II condemned the experiment, as did Roman Catholic and a number of Protestant leaders in America. At the White House, President Bush repeated his objection to cloning human embryos.

PRESIDENT GEORGE W. BUSH: The use of embryos to clone is wrong. We should not, as a society, grow life to destroy it.

ABERNETHY: We want to examine now what the scientists did in Worcester, Massachusetts, and what the implications are. Rick Weiss covers biotechnology for THE WASHINGTON POST.

Rick, welcome. What did the scientists report?

RICK WEISS (THE WASHINGTON POST): This is the first time anyone has made a cloned human embryo. That is, an embryo -- a single cell. It has been done before with farm animals but never before with people.

ABERNETHY: And it's perfectly legal?

MR. WEISS: It's legal as long as you do it with your own private money and with no federal funds.

ABERNETHY: Why do the scientists think this is ethical?

MR. WEISS: The idea is to get some stem cells from these embryos. These are cells that can be grown into all kinds of tissues that might then be used for replacement parts, basically, to help cure a lot of degenerative diseases. They also feel like it may be ethical because they are not even convinced that these things are really embryos: they are made by cloning, not by fertilization, and they are so young that it's not clear to them at least, and to some people, that they have the kind of moral standing that an embryo would have.

ABERNETHY: But at the same time, anything involving cloning sets off great alarms, doesn't it?