Poor weather has been hampering the search for seven still missing after Thursday's avalanche on Broad Peak.
The US president's latest comments come weeks after he offered Kyiv the right to make the missiles.
Brazil has argued the visit could have been used to raise suspicions about the electoral system's reliability ahead of October's vote, which the US state department rejects.
President Donald Trump had blamed "sick" vandals, and a former Olympian had been charged, but prosecutors now say contractors caused the damage.
Investigators hope the notes' "distinct linguistic characteristics" may be recognised by a member of the public.
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Race to rescue remaining climbers after deadly avalanche in Pakistan
Poor weather has been hampering the search for seven still missing after Thursday's avalanche on Broad Peak.
Trump now 'not sure' about letting Ukraine build Patriot missiles
The US president's latest comments come weeks after he offered Kyiv the right to make the missiles.
Brazil's president confirms two US government officials were denied visas over election interference fears
Brazil has argued the visit could have been used to raise suspicions about the electoral system's reliability ahead of October's vote, which the US state department rejects.
Trump administration drops Reflecting Pool vandalism charge and admits 'botched' repairs
President Donald Trump had blamed "sick" vandals, and a former Olympian had been charged, but prosecutors now say contractors caused the damage.
'Our hearts are in ruins,' Savannah Guthrie says after kidnapped mother's ransom notes released
Investigators hope the notes' "distinct linguistic characteristics" may be recognised by a member of the public.