ISLAMABAD, PAKISTAN - Countless U.S. officials in recent years have lectured and listened to Gen. Ashfaq Kayani, the man many view as the most powerful in Pakistan. They have drunk tea and played golf with him, feted him and flown with him in helicopters.

But they have yet to persuade him to undertake what the Obama administration's recent strategy review concluded is a key to success in the Afghan war - the elimination of havens inside Pakistan where the Taliban plots and stages attacks on coalition troops in Afghanistan.

Kayani, who as Pakistan's army chief has more direct say over the country's security strategy than its president or prime minister, has resisted personal appeals from President Obama, U.S. military commanders and senior diplomats. Recent U.S. intelligence estimates have concluded that he is unlikely to change his mind anytime soon. Despite the entreaties, officials say, Kayani doesn't trust U.S. motivations and is hedging his bets in case the American strategy for Afghanistan fails.

In many ways, Kayani is the personification of the vexing problem posed by Pakistan. Like the influential military establishment he represents, he views Afghanistan on a timeline stretching far beyond the U.S. withdrawal, which is slated to begin this summer. While the Obama administration sees the insurgents as an enemy force to be defeated as quickly and directly as possible, Pakistan has long regarded them as useful proxies in protecting its western flank from inroads by India, its historical adversary.

"Kayani wants to talk about the end state in South Asia," said one of several Obama administration officials who spoke on the condition of anonymity about the sensitive relationship. U.S. generals, the official said, "want to talk about the next drone attacks."

The administration has praised Kayani for operations in 2009 and 2010 against domestic militants in the Swat Valley and in South Waziristan, and has dramatically increased its military and economic assistance to Pakistan. But it has grown frustrated that the general has not launched a ground assault against Afghan Taliban and al-Qaeda sanctuaries in North Waziristan.

Kayani has promised action when he has enough troops available, although he has given no indication of when that might be. Most of Pakistan's half-million-man army remains facing east, toward India.

In recent months, Kayani has sometimes become defiant. When U.S.-Pakistani tensions spiked in September, after two Pakistani soldiers were killed by an Afghanistan-based American helicopter gunship pursuing insurgents on the wrong side of the border, he personally ordered the closure of the main frontier crossing for U.S. military supplies into Afghanistan, according to U.S. and Pakistani officials.

In October, administration officials choreographed a White House meeting for Kayani at which Obama could directly deliver his message of urgency. The army chief heard him out, then provided a 13-page document updating Pakistan's strategic perspective and noting the gap between short-term U.S. concerns and Pakistan's long-term interests, according to U.S. officials.

Kayani reportedly was infuriated by the recent WikiLeaks release of U.S. diplomatic cables, some of which depicted him as far chummier with the Americans and more deeply involved in Pakistani politics than his carefully crafted domestic persona would suggest. In one cable, sent to Washington by the U.S. Embassy in Islamabad last year, he was quoted as discussing with U.S. officials a possible removal of Pakistan's president and his preferred replacement.

On the eve of the cable's publication in November, the normally aloof and soft-spoken general ranted for hours on the subject of irreconcilable U.S.-Pakistan differences in a session with a group of Pakistani journalists.

The two countries' "frames of reference" regarding regional security "can never be the same," he said, according to news accounts. Calling Pakistan America's "most bullied ally," Kayani said that the "real aim of U.S. strategy is to de-nuclearize Pakistan."