GENEVA, Switzerland - The United States unveiled a strategy to crack down on biological weapons yesterday that does not include any international enforcement, continuing the Bush administration's rejection of binding verification plans.

The U.S. undersecretary of state for arms control, Ellen Tauscher, said she wanted to revitalize the Biological Weapons Convention, which Washington walked out of in 2001 when it rejected international monitoring of military and pharmaceutical research.

But Tauscher expressed the same key reservation.

"The Obama administration will not seek to revive negotiations on a verification protocol to the convention," she told diplomats in Geneva.

The 1972 convention, ratified by 163 countries, bars the development, trade, and use of biological weapons such as anthrax, smallpox, and other toxins that could bring devastating effects to civilian populations. But the Cold War treaty was drawn up without enforcement provisions.

After the Soviet Union fell, diplomats began negotiating a new protocol for the ban that would have opened up participating countries to international monitoring.

The talks dragged on for almost a decade and were nearly finished when the Bush administration suddenly pulled out shortly after the Sept. 11 attacks.

At the time, Washington said the proposed inspection system would not work and would expose U.S. secrets to enemies and rivals. There have been no advances in global disarmament talks since.

"Our long-term goal is to develop mechanisms to verify compliance with this convention," said Swedish Ambassador Magnus Hellgren, who was representing the 27-nation European Union.

Hellgren, one of about 100 diplomats who saw Tauscher's presentation, said the United States was making a "welcome contribution." But he said he would reserve his verdict on the Obama administration's commitment to the process until 2011, when the entire convention will be reviewed.

Tauscher noted that the danger from biological agents had grown with the development of new science and global terrorism.

But, she said, "it is extraordinarily difficult to verify compliance."

A binding treaty on verification could not "keep pace with the rapidly changing nature of the biological-weapons threat," Tauscher said.

She said countries should act in a "voluntary" manner to build greater confidence in the convention.