Michele Kelemen

In written testimony to Congress, Taylor said he "became increasingly concerned" about informal policymaking, driven by Rudy Giuliani, that diverged from official U.S. policy on Ukraine.

Ambassador Taylor, who's serving as the interim head of the U.S. diplomatic mission to Ukraine, is expected to appear before a House panel participating in the impeachment inquiry into the president.

Every administration uses ambassadorships to reward big political donors. But unlike other political appointees, donors don't always have strong resumes in business politics and foreign affairs.

The acting U.S. ambassador to Ukraine is also caught up in the impeachment inquiry. William Taylor is expected to be asked to appear next week before the House committees investigating the president.

Career diplomats are increasingly being subpoenaed by the House Committees leading an impeachment inquiry. They've raised concerns about President Trump's lawyer, Rudy Giuliani's dealings.

President Trump's former national security adviser John Bolton reportedly was trying to caution others about Rudy Giuliani's efforts in Ukraine. Giuliani is Trump's personal attorney.

Marie Yovanovitch, the former ambassador to Ukraine, says she was pushed out of her role based on "unfounded and false claims by people with clearly questionable motives."

Secretary of State Mike Pompeo is blocking employees from cooperating with the House committees leading an impeachment inquiry. The move is raising tensions between political and career officials.

Who's who in the recently-released texts between government officials working on the U.S.-Ukraine relationship? And what do they mean for the impeachment inquiry?

Volker, who was named in a whistleblower complaint about President Trump's contact with Ukraine, resigned as U.S. special envoy to the country last week and is being deposed on Thursday.

Former U.S. Special Envoy for Ukraine Kurt Volker is scheduled to appear before congressional committees on Thursday over his involvement in the Ukraine whistleblower controversy.

The State Department's inspector general has requested an urgent meeting with key congressional committees on Ukraine. The briefing comes amid the House impeachment inquiry of President Trump.

The State Department made a new push in August to investigate emails on Hillary Clinton's private server. Former officials have been called again, in what seems to be a politically motivated investigation.

Diplomatic trade groups are urging Americans to respect diplomats' "non-partisan, non-political" work. This comes as the former ambassador to Ukraine is being pilloried by the Trump administration.

Ukraine President Volodymyr Zelenskiy makes his U.N. debut at a time when he's at the center of a U.S. political scandal. He had been hoping for international support to counter Russian aggression.

One year after world leaders laughed at President Trump, he returned to the U.N. General Assembly to underscore his America First agenda. He also held private meetings leaders from the U.K. and Iraq.

The U.S. is trying to use the United Nations General Assembly to build up international pressure on Iran as it points blame at Iran for a recent attack in Saudi Arabia. Iran denies the accusation.

Secretary of State Mike Pompeo visits Saudi Arabia to discuss the recent attack on its oil facilities.

Kelly Craft is expected to take up her job as U.S. Ambassador to the U.N. on Thursday.

Kelly Craft is expected to take up her job as U.S. Ambassador to the U.N. on Thursday. She's a Republican donor and is married to a billionaire coal executive. Craft is likely to take a much lower profile than her predecessor, Nikki Haley.