WASHINGTON — The future of a key pillar of Israeli security could rest with the fate of a few dozen pro-democracy activists in Egypt.

After Egyptian authorities filed charges on Feb. 6 against 43 American and other foreign pro-democracy activists who worked in the country, leading members of Congress issued stern warnings about a possible cutoff in U.S. aid to Egypt. If that aid disappears, it could have significant implications for Israel-Egypt relations and U.S. influence in the region — the aid has been a crucial moderating lever keeping the peace between Israel and Egypt for more than three decades.

While the congressional threats to cut assistance to Egypt are just threats for now, the increasingly stern warnings from Washington underscore a deterioration in the U.S.-Egypt relationship amid the chaos of post-Mubarak Egypt.

The most potent threat to Egyptian assistance came from Rep. Kay Granger (R-Texas), the chairwoman of the foreign operations subcommittee of the U.S. House of Representatives Appropriations Committee.

“The harassment of Americans who are in Egypt trying to help build their democracy is unacceptable,” Granger said last week after the charges were filed in Egypt against 16 U.S. citizens, including Sam LaHood, the son of U.S. Transportation Secretary Ray LaHood. At least six of the Americans remain in Egypt and are barred from the leaving the country, The New York Times reported.

“Not one more dollar should flow to the government of Egypt until the secretary of state can assure the American people that this issue is resolved,” Granger said.

U.S. officials have been scrambling to figure out who to deal with as Egypt has descended into disarray, with a soccer riot Feb. 1 devolving into a free-for-all that left at least 74 people dead. Administration officials have reached out to the Egyptian military government, to secular parties and to the Islamists who won the recent parliamentary elections. But a year after Mubarak’s ouster, Egypt’s future is still very much uncertain.

The stakes are high, with implications not just for the peace treaty that has kept Israel’s southern border mostly quiet for decades, but broader American capabilities in the region, including how the United States addresses tensions with Iran.

The immediate dangers are to U.S. influence in helping shape the outcome of pro-democracy movements elsewhere in the region that are likely to take their cues from Egypt, the most populous and historically most important Arab country. There also are tactical dangers to the access that U.S. forces have in a region where they might soon deploy to contain any Iranian threat to cut off oil supplies.

“The aid was not only supposed to undergird the peace treaty but security arrangements, U.S. overflights, Suez Canal access,” said David Schenker, a former Pentagon Middle East desk officer who is now an Egypt expert at the Washington Institute for Near East Policy.

In the short term, a cutoff in assistance to the Egyptian government would not precipitate a war with Israel, experts say; no party in Egypt, however hostile it is to Israel ideologically, wants to invite the uncertainty of conflict with a powerful neighbor.

“The Egyptians have their own reasons to keep the peace treaty and abide by its terms,” said Ed Abington, a former diplomat in the region who subsequently joined a Washington firm that lobbied for Arab governments.

But, he added, “if we cut off assistance, we jeopardize the relationship we’ve had since Anwar Sadat. That would be bad for Egypt and the United States. We don’t want to push Egyptians away.”

Should matters deteriorate, congressional action may be inevitable. Adding their voices to Granger’s call were Rep. Ileana Ros-Lehtinen (R-Fla.), the chairwoman of the House Foreign Affairs Committee, and Sen. Ben Cardin (D-Md.), the chairman of the Senate subcommittee on international development and foreign assistance. Cardin said the United States should “re-evaluate the status of our bilateral relationship” with Egypt.

“One of the benefits of assistance was that we were going to have insight and influence,” Schenker said. “If they’re going to be overtly hostile, Congress has its own prerogative. It is a lot of money for the American taxpayer to give to a country that is not a friend.”

Whether the prosecution of LaHood and others could trigger actual cuts in the approximately $1.5 billion in U.S. assistance to Egypt is unclear. Newly stringent language about U.S. aid to Egypt in the 2012 congressional appropriations specifies that Egypt must meet “its obligations under the 1979 Egypt-Israel Peace Treaty” and support “the transition to civilian government including holding free and fair elections; implementing policies to protect freedom of expression, association, and religion, and due process of law.”

Nor is it clear yet whether due process has been violated for the 19 Americans who face charges. Egypt watchers say the activists likely were targeted by Fayza Abul Naga, Egypt’s minister for international cooperation, a holdover from the regime of deposed President Hosni Mubarak who is known for her anti-Western animus. The activists may have created an opportunity for Naga by not obtaining the proper licenses and by violating a recent travel ban on U.S. aid workers.

That has led to a paradox, according to Schenker.

“If you look at this from the SCAF’s position,” he said, using the acronym for the Supreme Council of the Armed Forces, the interim military government in Egypt, “the White House has been beating them up for eight months for democratizing enough, and now we’re asking them to intervene in the judiciary, which is supposed to be independent.”

If anything, the arrests pointed to a broader problem vexing U.S. attempts to engage with Egypt, Schenker said: The country’s transition is increasingly chaotic.

“We knew Egypt was going to be populist post-Mubarak, and this was to be anticipated,” he said. “The challenge for us is to try and maintain a relationship with this country.”