Russia's Ministry of Foreign Affairs said on Thursday it would issue a formal note of protest to the U.S. embassy in Moscow after authorities caught three U.S. diplomats in a restricted area near a secret test site, the TASS news agency reported.

The diplomats, among them U.S. military and naval attaches, were removed from a train on Monday in northern Russia near the site of a mysterious military testing accident that took place in August.

A U.S. State Department spokesman said the diplomats had been on an official trip and that they had notified Russian authorities in advance of their travel plans.

But Russia's foreign ministry said the diplomats had been found in a restricted area more than 40 kilometres (25 miles)from the city, Arkhangelsk, which they had said they planned to visit.

https://english.ahram.org.eg/News/353050.aspx