1. Trading blows China’s tariff retaliation

China has unveiled duties of up to 25% on US food imports including pork, fruit, nuts and wine in retaliation for new steel and aluminium tariffs instituted by Donald Trump’s administration, the Financial Times reports. The duties on 128 US products will "safeguard China’s interests and balance the losses caused" by the higher US tariffs, Beijing says. China runs a trade surplus with the US, which means it has a lot to lose in the advent of an all-out trade war.

The new duties are a response to higher tariffs, not the 25% levy on up to US$60bn of annual imports from China that Trump has said is coming. That leaves open the prospect that Beijing could produce a tougher response in the future.

2. New broom in Botswana

Mokgweetsi Masisi was sworn in as the new president of Botswana this weekend, taking over from Ian Khama, who has completed the maximum 10 years in office. Much like Khama, Masisi hails from a political family.

The retired teacher will be tasked with diversifying Botswana’s economy away from diamonds. That may be the best way to tackle the country’s 18% unemployment rate.

3. Oh, just close the book already

Facebook is bad for your health. In a study published in the Journal of Social Psychology titled "The Burden of Online Friends", participants’ levels of cortisol, the stress hormone, were found to have reduced after five days of spending no time on the social networking site.

However, lead author Eric Vanman says more research is needed. The study doesn’t show, for example, whether someone’s cortisol would increase again before they decided they were missing out and returned to the site.