If the case is not resolved, Congress and the Obama administration have vowed to cut off the $1.55 billion in annual aid to Egypt, potentially rupturing the three-way alliance among Washington, Cairo and Jerusalem that has been a linchpin of regional stability.
Doubts about the strength of the Brotherhood's commitment to its promises raise particular concerns in the United States and Israel, which considered the Mubarak government's commitment to the peace agreement a linchpin of regional stability.
But it is the victory in Egypt — the largest and once the most influential Arab state, an American ally considered a linchpin of regional stability — that has the potential to upend the established order across the Middle East.
Some analysts believe that Egypt would have to leave the treaty in place because it is "a linchpin of regional stability" and "ensures peaceful borders at a time when Egypt can ill afford the cost of a military buildup and its economy teeters on the brink of collapse".
The pact is considered a linchpin of regional stability, and the statements, from at least two senior leaders of the party, the political arm of the Muslim Brotherhood, represent the first time that Egyptians have explicitly raised it during an escalating standoff over the crackdown.
"Ukraine is a linchpin for stability in Europe," said Olexiy Haran, a professor of comparative politics at Kiev Mohyla University.
But to the relief of Obama administration officials, Mr. Morsi so far has not hinted at such a move, which would threaten the 1979 Camp David peace treaty between Israel and Egypt, a linchpin for stability in the region in Washington's view.
The southern portion of the country, separated from the north by a high mountain chain, seems mired in an intractable ethnic conflict yet is the linchpin for stability in Kyrgyzstan, a central challenge facing the new government to be formed after parliamentary elections on Sunday.
On the contrary, China has been a linchpin for stability and development in this important region.
