THE TRUMP administration has surprised Egypt’s autocratic government by delaying or diverting nearly $300 million in U.S. aid. It’s an appropriate response to the most severe repression in the Arab country’s modern history and to the regime’s collaboration with North Korea. But for those who believe President Trump has suddenly lost his affection for Egyptian strongman Abdel Fatah al-Sissi, some perspective is necessary: The actions were largely forced by congressional legislation, and they are unlikely to have much effect unless there is follow-up in the next federal budget.

Congress has banned military aid to foreign forces suspected of human rights abuses, and it has specifically linked 15 percent of the $1.3 billion in annual military aid to Egypt to human rights. At the same time, the United States has been unable to spend hundreds of millions of dollars in Egyptian economic aid because of resistance from the regime, which is deeply hostile to American support for nongovernment groups.

The administration’s action affects $65 million in military aid from fiscal year 2014 that was set to expire on Sept. 30 and that could not be justified under the so-called Leahy amendment linking foreign military aid to human rights performance. An additional $30 million in economic aid — unspent because of Cairo’s noncooperation — was withdrawn.

Meanwhile, the administration issued a waiver to avoid the congressional human rights restrictions on $195 million more in military aid. It says it will hold that money until the Sissi regime meets new terms set by the administration, including mitigating a new law that places drastic controls on nongovernmental organizations and reducing Egypt’s cooperation with North Korea.

Mr. Sissi should not be surpised by this: He ignored strong messages from Washington on North Korea and the nongovernmental organization law. He may have calculated that Mr. Trump would fail to hold him accountable — as happened under President Barack Obama, who criticized the regime’s human rights abuses but ultimately handed over all funding.

The Trump administration will be tempted to follow the same course. Instead, it — and Congress — should fundamentally reform aid to Egypt. The administration’s budget for 2018 includes no cut in aid to Cairo even while slashing assistance to virtually every other country in the world. By way of contrast, Tunisia, the only country to emerge from the Arab Spring as a democracy, under a government eager to cooperate with the United States on counterterrorism, is slated for a 67 percent cut.

What makes that plan particularly perverse is that this year offers a rare opportunity for reform. For years, Egyptian military aid has been delivered though a system called “cash-flow financing” that allows Cairo to commit to the purchase of big-ticket items such as F-16 fighter planes years in advance. The practice made it virtually impossible to reduce U.S. aid without breaking contracts with American corporations.

Though it shied away from funding cuts, the Obama administration engineered an end to cash-flow financing as of this year. That provides a chance to undertake a wholesale restructuring of the aid. Some should be diverted to funding the fight against the Islamic State, and all should be linked to significant human rights conditions, without the waiver loophole the administration just used.

Some of the withheld aid should be transferred to Tunisia. Why not reward a struggling democracy that, unlike its neighbor, is eager to partner with the United States?