The Unit­ed States on Wednes­day at­trib­uted the drone at­tack that killed three U.S. ser­vice mem­bers in Jor­dan to the Is­lam­ic Re­sis­tance in Iraq, an um­brel­la group of Iran-backed mili­tias, as Pres­i­dent Joe Biden weighs his re­sponse op­tions to the strike.

The at­tri­bu­tion comes as Iran threat­ened on Wednes­day to “de­ci­sive­ly re­spond” to any U.S. at­tack on the Is­lam­ic Re­pub­lic af­ter the U.S. said it holds Tehran re­spon­si­ble. The U.S. has sig­naled it is prepar­ing for re­tal­ia­to­ry strikes in the Mideast in the wake of the Sun­day drone at­tack that al­so wound­ed at least 40 troops at Tow­er 22, a se­cre­tive base in north­east­ern Jor­dan that’s been cru­cial to the Amer­i­can pres­ence in neigh­bour­ing Syr­ia.

Na­tion­al Se­cu­ri­ty Coun­cil spokesman John Kir­by said Wednes­day the U.S. be­lieves the at­tack was planned, re­sourced and fa­cil­i­tat­ed by the Is­lam­ic Re­sis­tance in Iraq, an um­brel­la group that in­cludes the mil­i­tant group Kataib Hezbol­lah. He said Biden “be­lieves that it is im­por­tant to re­spond in an ap­pro­pri­ate way.”

Kir­by said Biden was con­tin­u­ing to weigh re­tal­i­a­tion op­tions to the at­tack but said “the first thing you see won’t be the last thing,” adding it “won’t be a one-off.”

Kir­by dis­missed a state­ment by Iraqi mili­tia Kataib Hezbol­lah an­nounc­ing “the sus­pen­sion of mil­i­tary and se­cu­ri­ty op­er­a­tions against the oc­cu­pa­tion forces in or­der to pre­vent em­bar­rass­ment to the Iraqi gov­ern­ment.” He said that the group can’t be tak­en at face val­ue, and he added, “they’re not the on­ly group that has been at­tack­ing us.”

Biden, mean­while, is set to at­tend the somber re­turn of the fall­en troops to U.S. soil on Fri­day at Dover Air Force Base in Delaware, known as a dig­ni­fied trans­fer, the White House an­nounced.

Any ad­di­tion­al Amer­i­can strikes could fur­ther in­flame a re­gion al­ready roiled by Is­rael’s on­go­ing war on Hamas in the Gaza Strip. The war be­gan with Hamas at­tack­ing Is­rael on Oct. 7, killing some 1,200 peo­ple and tak­ing about 250 hostage. Since then, Is­raeli strikes have killed more than 26,000 Pales­tini­ans and dis­placed near­ly 2 mil­lion oth­ers from their homes, arous­ing anger through­out the Mus­lim world.

Vi­o­lence has erupt­ed across the Mideast, with Iran strik­ing tar­gets in Iraq, Pak­istan and Syr­ia, and the U.S. car­ry­ing out airstrikes tar­get­ing Yemen’s Houthi rebels over their at­tacks ship­ping in the Red Sea. Some ob­servers fear a new round of strikes tar­get­ing Iran could tip the re­gion in­to a wider war.

A U.S. Navy de­stroy­er in the wa­ter­way shot down an an­ti-ship cruise mis­sile launched by the Houthis late Tues­day, the lat­est at­tack tar­get­ing Amer­i­can forces pa­trolling the key mar­itime trade route, of­fi­cials said. The U.S. lat­er launched a new round of airstrikes tar­get­ing the Houthis.

The Iran­ian warn­ings first came from Amir Saeid Ira­vani, Iran’s am­bas­sador to the Unit­ed Na­tions in New York. He gave a brief­ing to Iran­ian jour­nal­ists late Tues­day, ac­cord­ing to the state-run IR­NA news agency.

“The Is­lam­ic Re­pub­lic would de­ci­sive­ly re­spond to any at­tack on the coun­ty, its in­ter­ests and na­tion­als un­der any pre­texts,” IR­NA quot­ed Ira­vani as say­ing. He de­scribed any pos­si­ble Iran­ian re­tal­i­a­tion as a “strong re­sponse,” with­out elab­o­rat­ing.

The Iran­ian mis­sion to the U.N. did not re­spond to re­quests for com­ment or elab­o­ra­tion Wednes­day on Ira­vani’s re­marks.

Ira­vani al­so de­nied that Iran and the U.S. had ex­changed any mes­sages over the last few days, ei­ther through in­ter­me­di­aries or di­rect­ly. The pan-Arab satel­lite chan­nel Al Jazeera, which is based in and fund­ed by Qatar, re­port­ed ear­li­er that such com­mu­ni­ca­tion had tak­en place. Qatar of­ten serves as an in­ter­me­di­ary be­tween Wash­ing­ton and Tehran.

“Such mes­sages have not been ex­changed,” Ira­vani said.

But Iran’s gov­ern­ment has tak­en note of the U.S. threats of re­tal­i­a­tion for the at­tack on the base in Jor­dan.

“Some­time, our en­e­mies raise the threat, and nowa­days we hear some threats in be­tween words by Amer­i­can of­fi­cials,” Rev­o­lu­tion­ary Guard com­man­der Gen. Hos­sein Sala­mi, who an­swers on­ly to Supreme Leader Ay­a­tol­lah Ali Khamenei, said at an event Wednes­day. “We tell them that you have ex­pe­ri­enced us, and we know each oth­er. We do not leave any threat with­out an an­swer.”

“We are not af­ter war, but we have no fear of war,” he added, ac­cord­ing to IR­NA.

Kir­by, for his part, said the U.S. doesn’t “seek a war with Iran. We’re not look­ing for a broad­er con­flict.”

On Sat­ur­day, a gen­er­al in charge of Iran’s air de­fens­es de­scribed them as be­ing at their “high­est de­fen­sive readi­ness.” That rais­es con­cerns for com­mer­cial avi­a­tion trav­el­ing through and over Iran as well. Af­ter a U.S. drone strike killed a top gen­er­al in 2020, Iran­ian air de­fens­es mis­tak­en­ly shot down a Ukrain­ian pas­sen­ger plane, killing all 176 peo­ple on board.

Mean­while, at­tacks by the Iran­ian-backed Houthi rebels con­tin­ue in the Red Sea, most re­cent­ly tar­get­ing a U.S. war­ship. The mis­sile launched Tues­day night tar­get­ed the USS Grave­ly, an Ar­leigh Burke-class guid­ed mis­sile de­stroy­er, the U.S. mil­i­tary’s Cen­tral Com­mand said in a state­ment. No in­juries or dam­age were re­port­ed.

A Houthi mil­i­tary spokesman, Brig. Gen. Yahya Sa­ree, claimed re­spon­si­bil­i­ty for the at­tack in a state­ment Wednes­day morn­ing, call­ing it “a vic­to­ry for the op­pres­sion of the Pales­tin­ian peo­ple and a re­sponse to the Amer­i­can-British ag­gres­sion against our coun­try.”

Sa­ree claimed the Houthis fired “sev­er­al” mis­siles, some­thing not ac­knowl­edged by the U.S. Navy. Houthi claims have been ex­ag­ger­at­ed in the past, and their mis­siles some­times crash on land and fail to reach their tar­gets.

The Houthis claimed with­out ev­i­dence on Mon­day to have tar­get­ed the USS Lewis B. Puller, a float­ing land­ing base used by the Navy SEALs and oth­ers. The U.S. said there had been no at­tack.

On Wednes­day, a U.S. mil­i­tary jet struck a sur­face-to-air mis­sile that was about to launch from Houthi-con­trolled Yemen, a U.S. of­fi­cial said. The mis­sile was deemed an im­me­di­ate threat and de­stroyed. The of­fi­cial spoke on the con­di­tion of anonymi­ty to pro­vide de­tails ahead of a pub­lic an­nounce­ment.

Since No­vem­ber, the rebels have re­peat­ed­ly tar­get­ed ships in the Red Sea over Is­rael’s of­fen­sive against Hamas in Gaza. But they have fre­quent­ly tar­get­ed ves­sels with ten­u­ous or no clear links to Is­rael, im­per­il­ing ship­ping in a key route for glob­al trade be­tween Asia, the Mideast and Eu­rope.

The Houthis hit a com­mer­cial ves­sel with a mis­sile on Fri­day, spark­ing a fire that burned for hours.

The U.S. and the Unit­ed King­dom have launched mul­ti­ple rounds of airstrikes tar­get­ing the Houthis as al­lied war­ships pa­trol the wa­ter­ways af­fect­ed by the at­tacks. The Eu­ro­pean Union al­so plans to launch a naval mis­sion in the Red Sea with­in three weeks to help de­fend car­go ships against the Houthi at­tacks, the bloc’s top diplo­mat said Wednes­day.

As­so­ci­at­ed Press writ­ers Nass­er Kari­mi in Tehran, Iran, and Tara Copp in Wash­ing­ton con­tributed to this re­port.

WASH­ING­TON (AP) —