AILSA CHANG, HOST:
The White House and State Department are declining to identify the Iranian threat that prompted the U.S. to send land-based bombers and an aircraft carrier strike group to the Persian Gulf region. National security adviser John Bolton said in a statement last night that the move comes in response to, quote, "a number of troubling and escalatory indications and warnings from Iran." NPR Pentagon correspondent Tom Bowman joins us now to talk about all of this. Hey, Tom.
TOM BOWMAN, BYLINE: Hey, Ailsa.
CHANG: So what do we know about these bombers and this aircraft carrier that got deployed?
BOWMAN: Well, we know about the aircraft carrier. We don't know about the bombers quite yet.
BOWMAN: What Bolton said is the U.S. Abraham Lincoln Carrier Strike Group will be heading over to the Persian Gulf region. It's now in the Mediterranean finishing up exercises. So it could be days or longer before it gets there. Bolton also said a, quote, "bomber task force," will be heading over as well. But what's unusual is that the Pentagon doesn't know at this point where those bombers will be coming from in the U.S. Usually when you announce something like this, Ailsa, you generally know which U.S. base will provide them. And oftentimes you announce this when the planes are actually in the air. That didn't happen in this case.
Here's another thing. It's almost unheard of for a national security adviser to announce this. It usually comes from the defense secretary or even the Navy just putting out a simple press release. It took many people by surprise, including lawmakers on Capitol Hill. But today the acting defense secretary, Patrick Shanahan, did put out a statement saying this is a prudent repositioning of assets in response to indications of a credible threat by Iranian regime forces.
CHANG: All that Secretary of State Mike Pompeo would say last night is that this has nothing to do with the fighting between Israel and Hamas in Gaza. So what could be behind this decision?
BOWMAN: Well, we really don't know. Israel Gaza fight is a separate issue. And we really don't know what he means when he says a number of troubling and escalatory indications and warnings. That's all we have. Now, Iranian forces or their proxies are not far from U.S. ground forces in Syria, Iraq and Yemen. But there are no indications, at this point, of any problems. Now, two years ago, the U.S. shot down two Iranian drones moving close to American-backed rebels in Syria. And that was it.
And actually, Ailsa, last year when I was in Syria, it was Russian mercenaries that were a threat, mounting an attack on these American-backed rebels and their U.S. advisers in northeast Syria. The U.S. responded with a withering air attack that killed more than 200 of these Russian mercenaries. And of course you have American ships in the Persian Gulf or that area, not far from Iran. But there are no indications, from officials I've talked with in the Navy or the Air Force, that either Iranian ships or aircraft have been threatening or unprofessional to U.S. warships. You did have an Iranian drone buzz an American ship, but that was two years ago.
CHANG: Now, this Wednesday does mark a year since the U.S. withdrew from the Iran nuclear deal and reinstated sanctions against Iran. How do you think this deployment, if at all, figures into that?
BOWMAN: Well, we don't know because the administration is, again, saying just indications and warnings. But the Trump administration - and particularly Bolton and Pompeo, both Iran hawks - are placing more pressure on Tehran. Besides pulling out of the nuclear agreement, imposing sanctions, they also declare the Iranian Revolutionary Guard is a terrorist organization.
BOWMAN: So clearly this is just putting more pressure on Iran.
CHANG: That's NPR Pentagon correspondent Tom Bowman. Thanks, Tom.
BOWMAN: You're welcome. Transcript provided by NPR, Copyright NPR.