Xi Jinping issued a stark warning to visiting US president Donald Trump as they began their landmark summit on Thursday , saying that mishandling of the Taiwan issue could lead to “clashes or even conflict”, describing it as “an extremely dangerous situation”. The warning came during closed-door talks on the first day of Mr Trump’s visit, the first by an American leader in nine years. The summit was intended to stabilise ties between the world’s two biggest powers amid mounting geopolitical tensions. The Chinese president welcomed Mr Trump with lavish diplomatic pageantry but his warning was a stark reminder that the issue of Taiwan , a self-governing island claimed by China as a breakaway province, remained a major irritant in bilateral relations.…