On July 25, 2019 (June 23, 2019 in the lunar calendar), the "telephone scandal" incident between the United States and Ukraine broke out. Trump and Zelensky On July 25, 2019, US President Trump had a 30-minute phone call with Ukrainian President Zelensky. On October 4, Democrats in the U.S. House of Representatives released information on exchanges between a group of senior U.S. and Ukrainian diplomats. This information shows that when US President Trump had a phone call with Ukrainian President Zelensky in July this year, he used the meeting between the two as soon as possible as a bargaining chip to pressure the other party to investigate former US Vice President and Democratic presidential candidate Biden and his son. The text of this batch of information exchanged between senior diplomats of the United States and Ukraine was provided by Kurt Volko, the special representative of the U.S. government for Ukraine who resigned not long ago. On the 3rd local time, Walko went to Congress to testify to the Foreign Affairs Committee, the Supervision Committee and the Intelligence Committee of the House of Representatives, explaining the relevant situation. This information shows that a few hours before Trump and Zelensky had a phone call on July 25 this year, Volko told Ukrainian Presidential Adviser Andriy Yermak, "If Zelensky can investigate and collect Biden and his son's relevant'black information ', then the two sides will finalize Zelensky's visit to the United States as soon as possible." After that, the two bargained by exchanging messages. At present, the White House has not made any response to these information texts. According to recent reports from the US media, in August this year, a US intelligence source accused Trump of "using military aid as a bargaining chip" in a telephone call with Zelensky, pressuring the other party to investigate Biden and his son. The Trump administration then blocked Congress from learning about the situation. This "telephone door" incident shocked the American ruling and opposition parties. Democrats accused Trump of abusing his power for personal gain and seeking foreign forces to interfere in the US presidential election. The U.S. House of Representatives launched an impeachment investigation into Trump on September 24th. On September 27th, the Foreign Affairs Committee, the Supervision Committee and the Intelligence Committee of the House of Representatives issued a subpoena to Secretary of State Pompeo, asking him to submit documents related to the "Telephone Gate" incident before October 4th this year to cooperate with the impeachment investigation. On October 4th, the three committees issued a summons to Vice President Pence, asking Pence to submit relevant documents before the 15th.