As much of Latin America moves to the left (albeit in varied ways), the latest action is in Ecuador. The government has purported to cancel its contract with U.S. multinational Occidental Petroleum in response to an alleged breach by Occidental. The USTR has said this appears to constitute a "seizure", and has terminated bilateral FTA negotiations.
Ecuador does have a BIT with the U.S., and Occidental's contractual rights appear quite valuable. So it is unlikely that this will end easily for Ecuador. In April, the U.S. claimed that Ecuador's newly enacted oil tax violated the BIT.