National security

President Donald Trump steps off Air Force One as he arrives Friday, July 12, 2019, at Andrews Air Force Base, Md. (AP Photo/Alex Brandon)

Rep. Alexandria Ocasio-Cortez, D-NY., left, testifies before the House Oversight Committee hearing on family separation and detention centers, Friday, July 12, 2019 on Capitol Hill in Washington. Also on the panel is Rep. Rashida Tlaib, D-Mich. (AP Photo/Pablo Martinez Monsivais)

FILE - In this July 10, 2018, file photo, former Trump national security adviser Michael Flynn leaves the federal courthouse in Washington, following a status hearing. Prosecutors won't call Flynn to testify at the upcoming trial of his former business partner. Court documents unsealed Tuesday, July 9, 2019, in federal court in Alexandria, Va., show prosecutors changed their mind about putting Flynn on the stand at next week's trial of Bijan Kian. (AP Photo/Manuel Balce Ceneta, File)

FILE - In this Friday, Oct. 20, 2017, file photo, British Ambassador Kim Darroch hosts a National Economists Club event at the British Embassy in Washington. Britain's ambassador to the United States resigned Wednesday, July 10, 2019, just days after diplomatic cables criticizing President Donald Trump caused embarrassment to two countries that often celebrate having a "special relationship." The resignation of Kim Darroch came a day after Trump lashed out at him on Twitter describing him as "wacky" and a "pompous fool" after leaked documents revealed the envoy's dim view of Trump's administration. (AP Photo/Sait Serkan Gurbuz, FIle)

Tallulah Campbell, 8, clears out driftwood and other debris in preparation of Tropical Storm Barry near New Orleans, La., Thursday, July 11, 2019. The area is normally a driveway at her family's home that is one of the few on land called batture on the outside of the Mississippi River levee at the border of Orleans and Jefferson Parishes. (AP Photo/Matthew Hinton)

Senate Minority Leader Sen. Chuck Schumer of N.Y., rides the escalator on Capitol Hill in Washington, Wednesday, July 10, 2019, as he heads to a briefing on election security. (AP Photo/Susan Walsh)

FILE - In this June 24, 2019, file photo, former national security adviser Michael Flynn, leaves the federal courthouse in Washington. with his lawyer Sidney Powell, left. Federal prosecutors say it’s too soon to take a position on sentencing for Flynn because he could still be a defense witness in the upcoming trial of a one-time business partner.(AP Photo/Manuel Balce Ceneta, File)

FILE - In this June 26, 2019, file photo, House Judiciary Committee Chairman Jerrold Nadler, D-N.Y., takes his seat for a hearing on Capitol Hill in Washington. The House Judiciary Committee is moving to authorize subpoenas for several people tied to special counsel Robert Mueller's report, including President Donald Trump's son in law, Jared Kushner, and former Attorney General Jeff Sessions. (AP Photo/J. Scott Applewhite, File)

Lucia Ascencio, of Venezuela, carries a suitcase after she and her husband and two sons were returned to Nuevo Laredo, Mexico, as part of the first group of migrants sent back to Mexico's Tamaulipas state under the so-called Remain in Mexico program for U.S. asylum seekers, Tuesday, July 9, 2019. Approximately 10 migrants crossed the border Monday to seek U.S. asylum and were sent back on Tuesday to wait as their applications are processed. (AP Photo/Salvador Gonzalez)

FILE - In this Feb.19, 2019 file photo, children line up to enter a tent at the Homestead Temporary Shelter for Unaccompanied Children in Homestead, Fla. A government spokesman says President Donald Trump’s administration is evaluating vacant properties near five U.S. cities as potential permanent sites to hold unaccompanied migrant children. Department of Health and Human Services spokesman Mark Weber said Wednesday that property is being assessed in and around Atlanta; Phoenix; Dallas; Houston; and San Antonio, Texas. (AP Photo/Wilfredo Lee, File)