Pentagon chief Jim Mattis is expected to pressure Pakistan to end its alleged ties to militant groups when he visits the country as part of a four-nation tour that began Friday.
Terrorism also will be a main focus of the U.S. defense secretary's stop in Egypt, which last week suffered what officials called the deadliest terror attack in the country's modern history.
Mattis' trip, which will also include stops in Kuwait and Jordan, comes as the U.S. military shifts its focus in the Middle East, after having largely driven out the Islamic State militant group from its self-declared caliphate in Iraq and Syria.
Another major priority is Afghanistan, where U.S. generals acknowledge the NATO coalition remains in a stalemate with Taliban insurgents after 16 years of war.
Thousands more U.S. troops are headed to Afghanistan, along with an increase in U.S. airpower, as part of a new White House strategy announced in August.
The plan also involves enlisting the help of neighboring Pakistan, which the United States has long accused of providing safe haven to the Afghan Taliban.
'One more time'
Pakistan denies sheltering the militants, and the issue has served as a major irritant to bilateral ties.
In October, Mattis said the United States would try "one more time" to work with Islamabad before taking "whatever steps are necessary" to address its alleged support for the militants.
U.S. officials have said Pakistan has not changed its behavior since President Donald Trump in August called out Pakistan for continuing to "harbor criminals and terrorists."
In response, the Trump administration is considering measures that include expanding U.S. drone strikes in Pakistan or downgrading the country's status as a major non-NATO ally, according to media reports.
More severe options include declaring Pakistan a state sponsor of terrorism or sanctioning individual Pakistani leaders suspected of having ties with the Taliban.
But the Trump administration is not likely to take any kind of punitive action for at least a few weeks, said Michael Kugelman, a South Asia analyst with the Woodrow Wilson Center, a global policy research group.
"I think it [the administration] wants to give the Pakistanis a bit more time to see if they're responding to the various demands that the United States made of them when it comes to cracking down on terrorists," said Kugelman.
One of the likelier U.S. responses, according to Kugelman, is expanding not only the geographic scope of the drone war but also the types of targets the United States goes after.
"I think we could start seeing the U.S. trying to target more Haqqani Network and Afghan Taliban targets," especially in the sparsely populated Baluchistan and Khyber Pakhtunkhwa provinces, he said.
The United States has much to lose if ties were to deteriorate. Pakistan controls U.S. military supply routes to landlocked Afghanistan, and could close them down, as it did in 2011. The U.S. would also like Pakistan to scale back its nuclear modernization, improve ties with India and stay engaged in the broader fight against Islamic militants.
But despite the risks, Michael O'Hanlon, a senior fellow at the Brookings Institution, a public policy research group, warns that Washington appears to be running out of patience.
"For many years we were trying to hold out hope that the Pakistanis would change their mind about Afghanistan and our role there," he said. "But those kinds of hopes aren't as prevalent anymore. And on balance, therefore, I think we are closer to using some of those tougher methods."
Mattis' four-country tour will begin in Egypt, which is reeling from last week's terror attack in the Sinai Peninsula. More than 300 people were killed when 25 to 30 militants carrying Islamic State flags attacked a mosque frequented by Sufi Muslim worshippers.
No group has claimed responsibility for the attack.
The militant group Sinai Province has been active in North Sinai since 2011, a remote desert region that borders the Gaza Strip. It has carried out several deadly attacks against police, soldiers and Coptic Christians.
Egyptian President Abdel Fattah el-Sissi has vowed to use "all brute force" necessary to respond to the attackers, and to secure the restive Sinai within the next three months.
Securing the area has proven problematic for Sissi. Egypt's military launched a large-scale military campaign against militants in September 2015. But, as evidenced by last week's attack, its effectiveness has been questionable.
Rights groups also have accused Egypt's military of carrying out extrajudicial killings and torture.
U.S. aid to Egypt
Human rights concerns could come up during Mattis' meeting with Egyptian leaders.
Earlier this year, the Trump administration denied Egypt $96 million in aid and delayed another $195 million over human rights concerns. Trump has since said he would consider reinstating the aid.
The Sinai attack could help justify that decision, said Timothy Kaldas, who specializes in U.S.-Egypt relations at the Tahrir Institute for Middle East Policy. He warned, though, that Egypt's rights record has not progressed since the aid suspension was announced.
"Moreover, there are no indications from the government, nor legislation under consideration, that suggest the rights situation will improve in the near future," Kaldas added.
The United States gives Egypt approximately $1.3 billion in military aid every year. Over the past three decades, Washington has given Cairo nearly $80 billion in military and economic assistance.
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