Premarket: Global shares cautious, dollar slips as trade concerns persist

European shares slid on Tuesday, along with U.S. stock futures, while the U.S. dollar lingered around a six-week low as erratic U.S. trade policies clouded market sentiment and investors turned defensive ahead of key developments later in the week. U.S. President Donald Trump and Chinese leader Xi Jinping will probably speak this week, the White House said on Monday, days after Trump accused Beijing of violating an agreement to roll back tariffs and trade restrictions. The call between the two leaders will be closely watched by markets, which have been roiled by tariff-induced trade tensions between the world's two largest…