Dow's futures contract slightly down after Trump's tariff threat

US stock index futures were slightly lower on Friday morning, after President Donald Trump announced he would impose a new 10% tariff on Chinese imports starting next month.

By 03:05 ET, Dow futures plunged 12 points, indicating a negative opening of more than 14 points. S & P and Nasdaq futures were slightly lower.

In a series of tweets on Thursday, the US president announced that a 10% fee would be imposed on Chinese goods valued at $ 300 billion. The tax will come into effect from September 1st.

This decision breaks a truce in the long-running trade war between the world's two largest economies, with investors worried that it will further disrupt global supply chains.

Chinese state media denounced Trump's tariff threat. The editor of the Global Times said that new charges would "in no way" bring the two parties closer.

Instead, Hu Xijn said via Twitter that the decision had pushed a global trade agreement "to get closer".

On the data side, investors are likely to be watching closely the last reading of non-farm wages at 8:30 am ET. Average hourly wages and unemployment rates for July will be released at the same time.

International trade data for June, factory orders for June and consumer confidence for July will also be released on Friday morning.

Chevron, Exxon Mobil and Arconic are among the most important companies about to announce their latest quarterly results before the opening bell.