Democrats in the US Senate have blocked a bill that would have given President Barack Obama the authority to finalise trade deals such as the Trans-Pacific Partnership and the Transatlantic Trade and Investment and Partnership with the EU.
The United States and China have announced a largely symbolic plan to implement new limits on carbon emissions, following a summit between Barack Obama and Xi Jinping at which both leaders played down suggestions of differences and rivalry.
President Petro Poroshenko has issued a decree instructing his government to consider temporarily closing Ukraine's eastern border with Russia to help halt its "intervention" in the ex-Soviet state's affairs.
Ukraine's parliament has ratified a landmark agreement on political association and trade with the European Union, the rejection of which last November by then President Viktor Yanukovych led to his downfall.
Russian prime minister Dmitry Medvedev has said the country will honour all its agreements with the European Union and Ukraine, but will trigger "protective measures" if a trade pact between the two comes into force early.