Myanmar's military crackdown that has caused a half-million Rohingya Muslims to flee to Bangladesh could destabilise the region and invite international terrorists, the US State Department said Thursday.

But Patrick Murphy, a senior US official for Southeast Asia, would not say whether the Trump administration would impose targeted sanctions against Myanmar's military.

Addressing the House Committee on Foreign Affairs, Murphy said security forces were to blame for a "disproportionate response" to Rohingya insurgent attacks six weeks ago. He equivocated on whether it amounted to ethnic cleansing, preferring instead to describe the situation as a "human tragedy."

That drew objections from lawmakers.

"We identify this as full-fledged ethnic cleansing," said Representative Ed Royce, the Republican committee chairman. Senior UN officials have used similar language.

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Murphy said that in addition to the half-million who have fled to Bangladesh, an estimated 200,000 people have been internally displaced in Myanmar's strife-hit Rakhine State. Despite government assurances that security operations halted a month ago, vigilantes are still reportedly committing arson attacks on Rohingya homes and blocking humanitarian assistance, he said.

"Burma's nascent democracy is at a turning point and a heavy-handed response invites international terrorists and challenges for other neighbors," Murphy said, referring to the alternative name for Myanmar, where long-standing sectarian tensions between majority Buddhists and the Rohingya have spiraled as the country has opened up.

He said the US has discussed the situation with other countries in Southeast Asia — where the Philippines, and Muslim-majority nations like Malaysia and Indonesia, have grappled with terrorist attacks and extremist violence.

Representative Eliot Engel, the committee's top-ranking Democrat, said the US should consider sanctions on Myanmar's military leadership and businesses that were lifted by the Obama administration to reward Myanmar's shift to democracy after five decades of direct military rule. A weak civilian government took power last year.

Murphy said the administration is "exploring all options available to us to effect change." The US already has substantial restrictions on the military and only very rarely grants US visas to members of the military and their families, he said.

He said the Min Aung Hlaing, the commander in chief of Myanmar's armed forces, "has enormous responsibility to stop the violence" and address security threats in a "proper manner." But he added that there are other contributors to the violence, including Rohingya militants and vigilantes — a reference to Buddhist thugs who have also attacked Rohingya.

Engel said satellite imagery and witness accounts indicate that Myanmar's military and security forces "have been carrying out an intentional, systematic policy to drive Rohingya from their homes in Burma and to burn their villages to the ground."

He said hundreds of Rohingya have been treated for gunshot wounds inflicted by security forces as they fled.

While Murphy steered clear of describing that as "ethnic cleansing," he pointed to comments by US Cabinet members, such as UN ambassador Nikki Haley who last week described it as a "brutal, sustained campaign to cleanse the country of an ethnic minority."