As President Donald Trump’s second administration continues its efforts to impose tariffs and to negotiate new international trade deals, Trump is expected this week to speak with Chinese President Xi Jinping, a White House adviser said Sunday

The White House’s efforts to foster an agreement between Russia and Ukraine are also expected to continue this week, with a direct meeting expected on Monday in Turkey. Secretary of State Marco Rubio and Russian Foreign Minister Sergei Lavrov spoke about the war on Sunday.

President Donald Trump said on social media that if the courts rule against his tariffs, it will empower other countries to impose retaliatory tariffs on the United States, leading to economic damage.

Such a ruling “would allow other Countries to hold our Nation hostage with their anti-American Tariffs that they would use against us,” Trump said in a post on his Truth Social site. “This would mean the Economic ruination of the United States of America!”