Ear­lier this month, a dra­matic event oc­curred in the war in Yemen that could even shock those numbed by the con­tin­ued pace of civil­ian ca­su­al­ties.

A mil­i­tary craft and he­li­copter re­port­edly en­gaged in an at­tack on a boat car­ry­ing over 140 So­mali refugees killing up­ward of 42 peo­ple on board.

De­spite ini­tially con­flict­ing ac­counts, the ev­i­dence points to the Saudi-led coali­tion.

On March 24, the U.N. re­ported that ac­cord­ing to sur­vivors’ ac­counts, the ves­sel “was hit by shelling from a Coali­tion war­ship, with­out any warn­ing, fol­lowed by shoot­ing from an Apache he­li­copter over­head.”

What has not re­ceived ad­e­quate at­ten­tion is the po­ten­tial role of the United States.

It will take time to sort out the de­tails of what ex­actly oc­curred, but this po­ten­tially brazen at­tack comes just as the White House is con­sid­er­ing in­creas­ing its in­volve­ment in the Saudi-led op­er­a­tions against the Iran­ian-back Houthi mili­tia in this Mid­dle East na­tion.

So, how might the United States be im­pli­cated given that it did­n’t come any­where close to pulling the trig­ger?

The United States pro­vides not only at­tack he­li­copters for the lead­ing mem­bers of the coali­tion, the Saudis and the United Arab Emi­rates. Of­fi­cial records re­veal that the United States also pro­vides parts and tech­ni­cal sup­port that pre­sum­ably at­taches to the life of the he­li­copters.

The De­fense De­part­men­t’s pub­lic no­ti­fi­ca­tion of a $1.9 bil­lion sale of multi-pur­pose he­li­copters used in mar­itime op­er­a­tions to Saudi Ara­bia in 2015, for ex­am­ple, in­cludes a guar­an­tee of “U.S. Gov­ern­ment and con­trac­tor en­gi­neer­ing, tech­ni­cal and lo­gis­tics sup­port ser­vices.”

This is a boil­er­plate part of the agree­ments for U.S.-man­u­fac­tured Apache and Black­hawk he­li­copters sold to the Saudis. (The same holds true for US-man­u­fac­tured he­li­copters sent to the UAE.) The De­part­ment of De­fense has also had a sub­stan­tial mil­i­tary pres­ence in Saudi Ara­bia to help them use the equip­ment.

Back in 1994, the Jus­tice De­part­men­t’s Of­fice of Le­gal Coun­sel warned U.S. of­fi­cials that they could be found guilty of aid­ing and abet­ting an of­fense by pro­vid­ing in­tel­li­gence in­for­ma­tion to for­eign gov­ern­ments who used that in­for­ma­tion to shoot down civil air­craft.

To il­lus­trate the point, the Jus­tice De­part­ment used the ex­am­ple of “the seller of gaso­line who knew the buyer was us­ing his prod­uct to make Molo­tov cock­tails for ter­ror­is­tic use.”

The U.S. pro­vi­sion of at­tack he­li­copters is even more di­rectly tied to the acts of the Saudis than the hy­po­thet­i­cal seller of gaso­line or a gun dealer.

The United States is re­spon­si­ble for con­tin­ued main­te­nance and sup­port of the sold equip­ment, the Saudi coali­tion has re­peat­edly en­gaged in bad acts, and the United States re­tains the abil­ity to sus­pend its lo­gis­ti­cal sup­port.

In the case of these highly so­phis­ti­cated he­li­copters, the U.S. sup­port is an ir­re­place­able part of the equa­tion.

“The Saudis have used weapons we have sold them in Yemen in ways that un­der­mine our for­eign pol­icy ob­jec­tive of end­ing the war and eas­ing hu­man­i­tar­ian suf­fer­ing there,” Tom Ma­li­nowski, who served as the top hu­man rights of­fi­cial at the State De­part­ment un­til Jan­u­ary 2017 told Just Se­cu­rity.

“There is a strong pol­icy ar­gu­ment for sus­pend­ing some sales, as Pres­i­dent Obama did, un­til con­cerns about these kinds of in­ci­dents are re­solved, and a pos­si­bil­ity of le­gal jeop­ardy for U.S. of­fi­cials if sales con­tinue de­spite con­tin­u­ing ev­i­dence of vi­o­la­tions of the laws of war.”

Even if we were not op­er­at­ing in the realm of crim­i­nal ac­tiv­ity, un­der in­ter­na­tional law one State can be held legally re­spon­si­ble for as­sist­ing an­other in in­ter­na­tion­ally wrong­ful acts. Those le­gal risks in­crease if the re­cip­i­ent is en­gaged in con­tin­u­ing and wide­spread vi­o­la­tions.

As a pol­icy mat­ter, this is the re­al­ity fac­ing the U.S. de­ci­sion of how close to get to the Saudi-led op­er­a­tions in Yemen.
But how do we know the at­tack on the refugees was car­ried out by the Saudis or Saudi-led coali­tion? We don’t for sure. But the real ques­tion is how much the U.S. gov­ern­ment knows.

Sev­eral eye­wit­ness ac­counts de­scribe the he­li­copter at­tack on the boat, in­clud­ing video of sur­vivor state­ments af­ter they came ashore. “The sur­vivors said they came un­der at­tack from an­other boat at 9 p.m., the crew used lights and shouted to sig­nal this is a civil­ian boat,” ICRC spokes­woman Iolanda Jaque­met told Reuters. “Nev­er­the­less, it did not have any ef­fect and a he­li­copter joined in the at­tack,” she said.

Only the coali­tion has mil­i­tary he­li­copters. Their op­po­si­tion, the Houthis, don’t. So­ma­lia has also fin­gered the coali­tion. The So­mali for­eign min­is­ter Ab­dis­alam Omer said on state-run ra­dio, “What hap­pened there was a hor­rific and ter­ri­ble prob­lem in­flicted on in­no­cent So­mali peo­ple. The Saudi-led coali­tion fight­ing in Yemen is re­spon­si­ble for it.”

So­ma­lia is it­self a mem­ber of the coali­tion, and thus likely has more in­for­ma­tion than other gov­ern­ments on coali­tion ac­tiv­ity.

The UAE, a more promi­nent mem­ber of the coali­tion who has been ac­tive in the area, in an un­prece­dented step called for in­ter­na­tional in­ves­ti­ga­tion into the in­ci­dent. This may serve the UAE’s ef­fort to cast them­selves as the more re­spon­si­ble part­ner com­pared to the Saudis.

“An of­fi­cial source in the UAE Armed Forces,” ac­cord­ing to Emi­rates state-run news, also “de­clared that the UAE Armed Forces have clearly rec­og­nized the non-mil­i­tary na­ture of the boat which was car­ry­ing a large num­ber of civil­ians. The source said that in the light of this in­for­ma­tion, the UAE Armed Forces ad­hered to the strict en­gage­ment rules pre­vent­ing them from tar­get­ing any non-mil­i­tary tar­gets.”

The source added that there was a pos­si­bil­ity the boat was tar­geted by Houthi forces.

The UAE state­ment im­plic­itly con­tra­dicts the spokesper­son for the coali­tion who de­nied that the coali­tion was even op­er­at­ing in the area. That de­nial is, in any case, hard to square with the coali­tion’s con­tin­u­ing and in­creased naval op­er­a­tions around the Hodeida port.

It would also not be the first time that cat­e­gor­i­cal de­nials of wrong­do­ing by the Saudi-led coali­tion’s spokesper­son have proven false.
The Saudis have not sup­ported an in­ter­na­tional in­quiry into the mat­ter. In the past, Riyadh has worked—with the ac­qui­es­cence of the U.S.—to block ef­forts at the U.N. to form an in­ter­na­tional body tasked with in­ves­ti­gat­ing the en­tire con­flict.

“As Yemen’s war en­ters its third year, the coali­tion has car­ried out what looks likely to be an­other war crime, this time with a he­li­copter at­tack­ing a boat filled with refugees and mi­grants flee­ing con­flict,” Kris­tine Beck­erle, Yemen re­searcher at Hu­man Rights Watch, told Just Se­cu­rity.

“In­stead of sus­pend­ing weapons sales to Saudi Ara­bia, given that U.S. arms have been re­peat­edly used in un­law­ful coali­tion at­tacks through­out this war, the US ap­pears poised to au­tho­rize even more sales, once again risk­ing com­plic­ity in fu­ture coali­tion at­tacks, and po­ten­tially ex­pos­ing U.S. in­di­vid­u­als to crim­i­nal li­a­bil­ity for aid­ing and abet­ting coali­tion crimes.”

In De­cem­ber, the Obama ad­min­is­tra­tion sus­pended the sale of pre­ci­sion guided mu­ni­tions to Saudi Ara­bia af­ter the Saudis used such U.S. man­u­fac­tured weapons in the strike on a fu­neral home. A se­nior US of­fi­cial told re­porters at the time that there was “ab­solutely no jus­ti­fi­ca­tion for the strike.”

The ques­tion that the U.S. ad­min­is­tra­tion will face is whether the Saudis are re­spon­si­ble for this most re­cent in­ci­dent and whether they can be trusted not to re­peat this kind of at­tac if so.