The United States has revoked the visa of Maria Luiza Viotti, Brazil’s ambassador to the US, amid a diplomatic dispute between the two countries. A senior State Department official said the move was in retaliation for Brazil’s refusal last month to issue visas to two American diplomats, and for its failure to grant agrément to Daniel Perez, President Donald Trump’s nominee for US ambassador to Brazil. Perez cannot take up the post until Brazil gives its approval, even though Trump nominated him in early June and the US Senate has not yet voted to confirm him. The US said it would restore the visa status if the dispute is resolved. Brazil’s foreign ministry confirmed that Viotti was in Brazil when she was notified of the visa revocation. Tensions have also spilled over into trade, after the US imposed additional tariffs on Brazilian imports, and Brazil vowed to defend its interests through diplomatic negotiations or by using World Trade Organization mechanisms if necessary.