The guest list last December included former British Prime Minister Tony Blair; former French President Nicolas Sarkozy; former Secretary of State Condoleezza Rice; Mr. Hadley, the Bush-era national security adviser; the American investors Mohamed A. El-Erian, David M. Rubenstein and Thomas S. Kaplan; and the Chinese computer scientist and investor Kai-Fu Lee.

Undeterred, the prince also included Mr. Dmitriev, the Russian businessman linked to Mr. Putin.

Prince Mohammed’s post-Arab Spring interventions have hardly stabilized the region. An aide he sent to Cairo to help turn around the moribund economy has returned in frustration.

Egypt’s military-backed government still depends on billions of dollars a year in assistance from the United Arab Emirates and its Gulf allies, and despite Emirati help and Israeli airstrikes, Cairo has not yet quelled a militant backlash centered in the North Sinai.

The isolation of Qatar has failed to change its policies. In Libya, Khalifa Hifter is mired in a bloody stalemate.

Prince Mohammed’s push in the Horn of Africa has set off a competition for access and influence among rivals like Turkey and Qatar. In Somalia, after allegations of bribery by the fragile central government, Emirati forces have shifted to the semiautonomous regions of Puntland and Somaliland.

Djibouti, alleging neglect, last year replaced its Emirati port managers with a Chinese rival.

“He thinks he is Machiavelli but he acts more like Mussolini,” said Bruce Riedel, a scholar at the Brookings Institution and a former official in the Central Intelligence Agency.

In Saudi Arabia, the Emirati prince has been embarrassed by the conclusion of American intelligence agencies that his Saudi protégé had ordered the brutal murder of Mr. Khashoggi, a Virginia-based Saudi dissident and Washington Post columnist. Their joint, four-year-old intervention in Yemen is turning into a quagmire, with horrific civilian casualties.