RACHEL MARTIN, HOST:
U.S. defense secretary Jim Mattis is in the Gulf country of Oman today meeting with its leader. Mattis' visit is seen as an effort to shore up Washington's ties with that country, and also as a part of an effort to prevent Iranian weapons from being shipped to Houthi rebels in neighboring Yemen. NPR national security correspondent David Welna is traveling with the defense secretary, and he joins me now. So David, just lay out for us what Secretary Mattis is doing there. What does he want from Oman right now?
DAVID WELNA, BYLINE: Well, you know, Rachel, Oman really is almost the only place in the Arabian Peninsula that's not in some kind of upheaval. A couple of factors might help explain that. One is that while this is a Muslim state, it's neither Sunni nor Shiite. Most Omanis are Ibadi Muslims, another school of Islam. So they have relations with both Sunni Saudi Arabia and its archrival, Shiite Iran. Omanis like to say they're friends of everyone and enemies of no one. So Oman is the only member of the Gulf Cooperation Council that's refused to join the Saudi-led coalition that's fighting in Yemen. And then there's Sultan Qaboos, who's been in power here for nearly half a century. Mattis, on the flight over here, had only praise for him.
JIM MATTIS: He's a very strategic leader there, Sultan Qaboos, and he recognizes the advantage that the violent extremists al-Qaida, ISIS, al-Qaida Arabian Peninsula, ISIS, the advantage they gain from that sort of disarray inside of Yemen.
WELNA: Yeah. Mattis clearly wants the Sultan's help blocking its extremist groups such as ISIS and al-Qaida that are fighting in eastern Yemen because they could spill over the border into Oman.
MARTIN: OK. So we hear Mattis there heaping praise on the sultan, the leader of Oman. But I mentioned in the intro, there are these reports that Iran has been smuggling weapons to Houthi rebels in Yemen through Oman's border. So is that not a problem? I mean, is the secretary of defense putting pressure on Oman to crack down there?
WELNA: Well, he's saying nothing. At least, not publicly. I think American officials are concerned about Iranian arms going through Oman, but anything they say would likely be in private. Oman is just too important a back channel for the U.S. in this region to get into some kind of public spat over this. And in fact there's a lot of open ocean here where the U.S. and other nations have had little luck lately interdicting Iranian weapons, while Oman's been able to get Iran's army to pull back from confronting U.S. ships in the Persian Gulf. And that's just another reason why this sultan is such a key ally.
MARTIN: Before I let you go, you were on the plane with the secretary of defense, on this flight. Reporters often get a chance to question the secretary on these trips, and there were some questions about Syria. What did the secretary have to say about the war there?
WELNA: Well, Mattis had some pretty tough words for Syria and Russia. He was referring to unconfirmed reports which the U.N. is still investigating that Syrian government forces used chlorine gas in attacks in Eastern Ghouta. Now, for the past five years, Syria's government has been banned from even possessing chemical weapons, much less using them, and Russia's the guarantor of that agreement. Mattis said that Russia's either been incompetent, or, as he put it, in cahoots with the Syrian regime, and he said that it would be very unwise for Syria to use weaponized gas.
MARTIN: All right. NPR's David Welna. Thanks, David. Transcript provided by NPR, Copyright NPR.