President Felix Tshisekedi
The operation to guard farmers who grow corn, beans, potatoes and manioc is known as "Secure Harvest" and it aims to allow them to work freely during the harvesting season and provide protection from militia groups who steal produce and kill people.
Rwanda cited repeated violations of its airspace by Congolese fighter jets as contributing to the heightened tensions.
Blinken, travelling in West Africa, spoke by telephone with Tshisekedi to congratulate him on his victory, the State Department said.
Provisional results from the single-round presidential ballot showed that Tshisekedi had won 73 per cent of the vote.
Voters in the DRC are voting for the second day today, in a general election marked by severe logistical troubles that meant some polling stations never opened yesterday.