On the night of Jan. 4, about 50 unarmed cadets many of them teenagers were practicing drills at a military academy in the Libyan capital of Tripoli. Suddenly, a missile landed in their midst. Twenty-six cadets died, with some of their bodies split into two.

The missiles origin: a Chinese drone operated by the United Arab Emirates the country that is now trying to buy its first armed American drones with President Donald Trumps blessing.

We were witnessing our colleagues dying, breathing their last breath, and we couldnt do anything it was an awful crime, a crime that has nothing to do with humanity, Abdul Moeen, a 20-year-old survivor of the attack, later told the BBC .

The UAE denies involvement in Libyas civil war. But U.S. intelligence proves thats a lie and that the Emirates carried out the strike on the academy, a U.S. official familiar with the assessment told HuffPost.

That intelligence confirms the BBCs conclusion in August that the UAE was to blame for the killings. Human Rights Watch has found other evidence tying the UAE to a November 2019 attack on a biscuit factory that killed eight civilians. Months earlier, a similar strike killed 53 migrants in a detention center, and United Nations officials reportedly concluded that the UAE was responsible , though they would only publicly describe the tragedy as evidence of the dangers and direct consequences on civilians of foreign interference.

As Congress debates Trumps massive $23 billion arms deal with the UAE, which includes Americas most advanced fighter jet and thousands of bombs and missiles in addition to the drones, lawmakers have a chance to prevent shipments that will almost certainly be used to kill innocent people, aggravate civil wars and boost the global perception that the U.S. has little regard for human rights.

The Senate will likely vote Wednesday on one or all of a set of bills to block those weapons transfers. The outcome depends on the decisions of a few Republican senators.

Sen. Rand Paul (R-Ky.) is helping lead the charge against the sale, and the 48-member Democratic caucus will almost certainly jointly vote against the deal, meaning the question now probably hangs on whether two more Senate Republicans will oppose the arms sale. One may be Sen. Lisa Murkowski (R-Alaska), whom anti-deal activists expect to vote against the transfer now based on private conversations. She has not yet publicly indicated how she will vote.

The congressional fight pits human rights and humanitarian groups, anti-war advocates and prominent mainstream voices on foreign policy against the sizable lobbying operations of the UAE, the defense industry, allies like former Trump Defense Secretary Jim Mattis , Trump aides and hawks who view the arms deal as a way to deter Iran.

The politics of the dispute are hugely significant. Voting to block the deal would serve as a final rebuke to Trump, despite his near-certain veto, and signal to the Biden administration that Congress would support the next president in stopping shipment of the weapons down the line. More broadly, the vote will signal how much Congress is thinking about exerting influence on foreign affairs after its no longer dealing with Trump, whose views differed from those of most lawmakers.

But the implications beyond Washington are even more important.

As the worlds largest arms exporter , the U.S. helps fuel almost every conflict on the planet. Most Americans spend little time thinking about how those weapons are actually used. In the case of the deal with the UAEs de facto ruler, Crown Prince Mohammed bin Zayed of Abu Dhabi the biggest such sale under Trump, who has behaved as an arms-dealer-in-chief the prospects for devastating consequences are very clear.

Opposing these arms sales should be an absolute no-brainer for any senator who champions human rights and opposes atrocities against civilians, Erica Fein of Win Without War, one of the groups opposing the deal, told HuffPost, listing instances in which the Emirates has defied international law. Continuing to sell weapons to the UAE knowing about these and other violations only continues U.S. complicity in these wars and the suffering of the people caught in them.

The UAE Embassy did not respond to a request for comment for this story.