US Secretary of State Condoleezza Rice has warned Europe against sending "the wrong signal" to China by ending an arms embargo on the country.
Condoleezza Rice is about to make her first official trip abroad
UK Foreign Secretary Jack Straw said last week the European Union could drop the embargo within six months.
It was imposed in 1989 after Chinese troops opened fire on protesters around Beijing's Tiananmen Square.
Washington has warned that if the blockade is lifted, China could embark on an arms-buying spree.
The US fears any weapons it buys could be used to threaten Taiwan, which Beijing considers as a renegade province of China.
The EU decided in December against lifting the embargo immediately, but the proposal is still under discussion.
France and Germany, both major arms exporters, back the move to lift sanctions.
However Ms Rice indicated she did not think the matter was settled yet, saying the US had a "good dialogue" with Europe over the issue.
"I think we're not resigned to anything. At this point we need to continue to discuss it and see what we can come up with," she said.
She said China's human rights record still needed to improve.
"I have to say that in a circumstance in which the embargo was levied because of human rights concerns out of Tiananmen, one has to be very careful not to send the wrong signal about human rights," she said.
Ms Rice, who was formally sworn in last week, leaves on her first official trip, to Europe and the Middle East, later this week.