U.S. and European military officials are increasingly concerned about the flights, even as Russian acts of sabotage have declined.

© Natalie Keyssar for The New York Times

U.S. and European military officials are increasingly concerned about the flights, even as Russian acts of sabotage have declined.

© Natalie Keyssar for The New York Times

The move comes weeks after the agency drafted a preliminary report contradicting President Trump’s contention that U.S. strikes had “obliterated” nuclear sites in Iran.

© Kenny Holston/The New York Times