Blame for Rohingya crisis lies with country's military leadership, Rex Tillerson says.
The current situation is "a real test of this power-sharing government", Rex Tillerson said during a public address in which he called on Myanmar's military leadership to decide on the direction "they want to play in the future of Burma because we see Burma as an important emerging democracy".
Burma is the U.S. government's preferred name for Myanmar.
The civilian side of the government is currently led by Aung San Suu Kyi, but she shares power with the Myanmarese military.
"What we’ve encouraged the military to do is, first, we understand you have serious rebel/terrorist elements within that part of your country as well that you have to deal with, but you must be disciplined about how you deal with those, and you must be restrained in how you deal with those," Tillerson said.
"And you must allow access in this region again so that we can get a full accounting of the circumstances," he added while speaking at the Center for Strategic and International Studies think tank in Washington.
Since Aug. 25, approximately 582,000 Rohingya have crossed Myanmar's western state of Rakhine into Bangladesh, according to the UN.
The U.S. has been able to get a few of its embassy staffers into Rakhine to assess the situation, Tillerson said as he stressed Washington is continuing to press for aid agency access to the conflict-riddled area.
The refugees are fleeing a military operation in which security forces and Buddhist mobs have killed men, women and children, looted homes and torched Rohingya villages. According to Bangladeshi Foreign Minister Abul Hasan Mahmood Ali, around 3,000 Rohingya have been killed in the crackdown.
Turkey has been at the forefront of providing aid to Rohingya refugees and President Recep Tayyip Erdogan has raised the issue at the UN.
The Rohingya, described by the UN as the world's most persecuted people, have faced heightened fears of attack since dozens were killed in communal violence in 2012.
Last October, following attacks on border posts in Rakhine's Maungdaw district, security forces launched a five-month crackdown in which, according to Rohingya groups, around 400 people were killed.
The UN documented mass gang rapes, killings -- including of infants and young children -- brutal beatings, and disappearances committed by security personnel. In a report, UN investigators said such violations may have constituted crimes against humanity.