Washington – The United States is deploying forces to the Middle East, in response to what administration officials say are threats of a possible attack by Iran or allied fighters on American troops in the region. White House national security adviser John Bolton said in a statement Sunday night that the U.S. is deploying the USS Abraham Lincoln Carrier Strike Group and a bomber task force to the U.S. Central Command region, an area that includes the Middle East.

Bolton said the move was in response to "a number of troubling and escalatory indications and warnings." He didn't provide details, but said the U.S. wants to send a "clear and unmistakable" message to Iran that "unrelenting force" would meet any attack on U.S. interests or those of its allies.

"The United States is not seeking war with the Iranian regime, but we are fully prepared to respond to any attack, whether by proxy, the Islamic Revolutionary Guard Corps, or regular Iranian forces," he said.

USS Abraham Lincoln in undated phhoto CBS News

A Defense Department official told CBS News chief Pentagon correspondent David Martin the U.S. has detected "a number of preparations for possible attack" on U.S. forces at sea and on land.

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"… There is more than one avenue of attack or possible attack that we're tracking," the official said. " … We've seen indications for a number of days but they were coming together in the last several days. … This has been moving pretty fast today (Sunday)."

The official said the decision to order the deployment was made Sunday.

The Pentagon had no immediate official comment on the Bolton statement.

Last month, President Trump announced the U.S. would no longer exempt any countries from U.S. sanctions if they continue to buy Iranian oil, a decision that primarily affects the five remaining major importers: China and India and U.S. treaty allies Japan, South Korea and Turkey and was meant to end Iranian oil exports.

Since then, Martin reports, U.S. intelligence has been picking up "chatter" about Iranian-backed Shia militias in Iraq attacking Americans. There are 5,200 U.S. troops in Iraq. At the time, U.S. intelligence analysts said the Iranian government appeared to be debating whether the issue of oil sanctions could be resolved through diplomacy.

The Abraham Lincoln and its strike group of ships and combat aircraft have been operating in the Mediterranean Sea recently.

Bolton's reference to the Central Command area would mean the Lincoln is headed east to the Red Sea and perhaps then to the Arabian Sea or the Persian Gulf. The U.S. Navy currently has no aircraft carrier in the Persian Gulf.

Bolton's mention of deploying a bomber task force suggests the Pentagon is deploying land-based bomber aircraft somewhere in the region, perhaps on the Arabian Peninsula.

Speaking to reporters while flying to Europe, Secretary of State Mike Pompeo said the actions undertaken by the U.S. had been in the works for a little while.

"It is absolutely the case that we have seen escalatory actions from the Iranians and it is equally the case that we will hold the Iranians accountable for attacks on American interests," Pompeo said. "If these actions take place, if they do by some third-party proxy, a militia group, Hezbollah, we will hold the Iranian leadership directly accountable for that."

Asked about "escalatory actions," Pompeo replied, "I don't want to talk about what underlays it, but make no mistake, we have good reason to want to communicate clearly about how the Iranians should understand how we will respond to actions they may take."

Asked if the Iranian action were related to the deadly events in Gaza and Israel - militants fired rockets into Israel on Sunday and Israel responded with airstrikes - Pompeo said, "It is separate from that."

The Trump administration has been intensifying a pressure campaign against Iran.

In addition to the move regarding U.S. sanctions, Washington also last month designated Iran's Revolutionary Guard as a terrorist group, the first time that was ever done to an entire division of another government.

Mr. Trump withdrew from the Obama administration's landmark nuclear deal with Iran in May 2018 and, in the months that followed, reimposed punishing sanctions including those targeting Iran's oil, shipping and banking sectors.

Bolton and Pompeo have in recent months spoken stridently about Iran and its "malign activities" in the region.