The U.S. embassy in Rīga is one of 18 American diplomatic missions to which a suspicious white powder was found in envelopes mailed earlier this month, the State Department and FBI have confirmed. The powder was not toxic.

The envelopes began to arrive at the embassies on Dec. 15, a State Department spokesman said Dec. 18.

In a Dec. 18 press briefing in Washington, D.C., State Department Spokesman Sean McCormack confirmed envelopes also were received at diplomatic missions in Berlin, Bern, Brussels, Bucharest, Copenhagen, Dublin, the Hague, Luxembourg, Madrid, Oslo, Paris, Prague, Reykjavik, Rome, Stockholm, Tallinn and Tokyo.

Each envelope, according to a FBI press release, was mailed from Texas and contained “a similar typewritten letter and a white powder substance.” Letters also were sent to 40 different governors’ offices around the U.S. In each case, field testing found the powder to be harmless. However, the FBI said, mailing such envelopes still is a federal crime and the matter remains under investigation.