President Barack Obama is expected to press Pakistani Prime Minister Nawaz Sharif on ties with the Taliban, nuclear safety and a range of other fraught issues Thursday when the troubled allies meet at the White House.

Despite efforts to smooth divisions behind handshakes, smiles and items of agreement, long-standing security concerns are likely to dominate the Oval Office discussions.

Islamabad's ties with the Afghan Taliban, support for terror groups that target India and the United States and its rapidly growing nuclear arsenal are seen by Washington as monumental security headaches.

Washington's relationship with Islamabad is a prickly one, born of a fraught inter-dependency but pollinated by mutual mistrust.

But relations were plunged into deep crisis when 9/11 mastermind Osama bin Laden was discovered to be living in a major Pakistani garrison city.

Since then Sharif has returned to the prime minister's office and brought an effort to find areas of cooperation, but officials point to little change in the attitude of Pakistan's powerful security services.

In a signal of that power, Sharif's visit will reportedly be bookended by visits from the head of Pakistan's Inter-Services Intelligence and the Chief of Army Staff Raheel Sharif.

"The bottom line is that there are a lot of deep disagreements between these two countries," said Michael Kugelman of the Woodrow Wilson Center.

"The US has simply lost patience after so many years of providing arms and money to the Pakistani military, the Pakistanis have simply not done what the US has repeatedly asked them to do in terms of cracking down on militants."

The meeting comes as the White House increasingly shifts its focus in South Asia to Pakistan's bitter rival India.

- Taliban to table? -

But Pakistan remains a key player in the region.

Obama recently announced that US troops would be staying in Afghanistan longer than he had promised, but the White House is keen to get the Taliban to the negotiating table.

The resurgent Islamists briefly captured a key northern Afghan city this month.

The US sees Pakistan as one of the few sources of influence over the extremists, and analysts say Washington will use the four-day trip to urge the prime minister to keep pushing for a new round of talks.

Experts say that the new Taliban leader Akhtar Mansour has close ties to Pakistan.

Kabul has accused Islamabad of harboring and nurturing Taliban insurgents -- allowing them to launch attacks in Afghanistan before melting back across the border.

Obama recently previewed his meeting with Sharif by saying "I will continue to urge all parties in the region to press the Taliban to return to peace talks and to do their part in pursuit of the peace that Afghans deserve."

If cooperation is not forthcoming, it is likely to result in growing calls for Washington to limit the transfer of weapons and funds to Islamabad.

Washington has also pressed Pakistan to crack down on radical groups like the Haqqani network and Lashkar-e-Taiba.

Ahead of Sharif's visit there have been suggestions that cooperation and a possible deal could be reached to more effectively control Pakistan's nuclear weapons.

During George W. Bush's presidency a deal was reached with India to normalize nuclear cooperation in return for safeguards.

But US officials have poured cold water on that suggestion and Sharif was quoted by Pakistani media as pointing out that he was Prime Minister when the country first become a declared nuclear state.