President Donald Trump signed into law a bill opening travel and diplomacy with Taiwan, something China warned against.
The Taiwan Travel Act allows U.S. diplomats from all levels to meet with their Taiwanese counterparts and allows Taiwan's diplomats "respectful conditions" when they come to the states. It also encourages growing an economic and cultural relationship.
But China doesn't consider Taiwan an independent country. Rather, it sees it as a rogue province that will eventually be folded back into the communist state — by use of force if necessary.
Chinese officials said the move broke with decades of precedent and violated the "One China" policy. Trump's administration has taken other steps to warm relations with the democratic island, such as approving a $1.3 billion arms sale last summer.