WASHINGTON — The White House announced on Sunday that the United States was sending an aircraft carrier strike group and Air Force bombers to the Middle East because of “troubling and escalatory indications and warnings” related to Iran.

The deployment was intended “to send a clear and unmistakable message to the Iranian regime that any attack on United States interests or on those of our allies will be met with unrelenting force,” said John R. Bolton, the national security adviser, in a statement released Sunday night.

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The announcement did not give any further information on the reasons for the commitment of military forces. An American military official said on Sunday night that whatever threat Mr. Bolton cited had most likely emerged in the previous 24 to 48 hours because as of late Friday, military analysts were not tracking any new, imminent or clearly defined Iranian or Iranian-backed threats against Americans in Iraq or the region.

Secretary of State Mike Pompeo, when asked by reporters about Mr. Bolton’s statement on a flight to Finland, said, “It’s something we’ve been working on for a little while.”