"China does not want a trade war with anyone, but China is not afraid of and will not recoil from a trade war," the country's embassy in Washington warned.
Officials said they did not know how many people were being held, but gunshots were heard inside.
Genetic research shows the six-inch-long skeleton belonged to a human fetus that had multiple genetic defects.
The weapons "will support U.S. foreign policy and national security objectives by improving the security of a friendly country," the State Department said.
President Donald Trump's new national security adviser is an ultra-hawkish figure whose foreign policy has led him to clash even with fellow Republicans.