The U.S. Embassy in Beijing has asked the Chinese government to increase security around the compound, the ambassador's residence and the four consulates in China, spokesman Bill Palmer said.
The Chinese government was being "cooperative," Palmer said, but he would not specify what steps were being taken.
The U.S. government issued a new worldwide warning Tuesday that Americans may be the target of terrorist attacks in the New Year period and said airport security at home was being tightened.
Groups of people, assembled for religious festivals or to mark the millennium, may be especially at risk, the State Department said in a stepped-up caution to citizens abroad.
In Pakistan, already tight security at the U.S. Embassy was increased. Cement blocks have been erected on roads leading to the embassy, forcing cars to slow down.
A dozen policemen with rifles stand guard outside the high-walled compound and more razor wire was put around the walls. Similar steps were taken at consulates in Lahore and Karachi.
Still, the mood at U.S. installations overseas was one of caution rather than alarm.
The U.S. military in Japan asked that staff "try not to participate in any events with large gatherings that might be a good terrorist target," said Col. Jeanette Minnich, spokeswoman for the U.S. Forces in Japan.
However, there have been no orders to cancel planned social activities, she said.
The embassy in Riyadh, the capital of Saudi Arabia, will continue to maintain high security, as usual, but will not cancel parties, reduce staff or send people home, officials said.
The embassies in Beijing and Tokyo said they knew of no terrorist threats specific to their regions.
By Eric Prideaux
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