Acting US homeland security chief Kevin McAleenan has resigned, becoming the latest in a long list of top officials to leave the administration.
Mr McAleenan's departure comes within days of the resignation of a top aide to US Secretary of State Mike Pompeo, as the controversy over the Trump administration's dealings with Ukraine deepens.
In a series of tweets late on Friday, US President Donald Trump announced the acting secretary would be leaving the post.
"Kevin McAleenan has done an outstanding job as Acting Secretary of Homeland Security. We have worked well together with Border Crossings being way down," Mr Trump tweeted.
"Kevin now, after many years in Government, wants to spend more time with his family and go to the private sector. Congratulations Kevin, on a job well done!"
President Donald Trump and Kevin McAleenan tours a section of the southern border wall. Source: AAP
Mr McAleenan served in the role for only six months, replacing Kirstjen Nielsen, who sat at the helm of the powerful agency for 18 months.
During Mr McAleenan's brief tenure, the Trump administration stepped up efforts to discourage an exodus of migrants from Honduras, Guatemala and El Salvador by asking Mexico to impede their transit and requiring them to apply for asylum in the first country they enter - meaning either Guatemala or Mexico.
"I want to thank the President for the opportunity to serve alongside the men and women of the Department of Homeland Security," McAleenan said in a tweet.
Honduras immigrants walk towards the US border crossing. Source: Republica.gt
"With his support, over the last 6 months, we have made tremendous progress mitigating the border security and humanitarian crisis we faced this year, by reducing unlawful crossings, partnering with governments in the region to counter human smugglers and address the causes of migration, and deploy additional border security resources."
Mr Trump said he would announce a new acting homeland security secretary next week, and that there were "many wonderful candidates."
Pompeo advisor resigns
Senior adviser to US Secretary of State Mike Pompeo Michael McKinley also resigned this week.
Mr McKinley, a career diplomat who has served as Mr Pompeo's policy adviser since May 2018, said in a note to staff that his departure after 37 years with the department was "personal".
Mr McKinley's departure comes as the congressional inquiry on impeachment proceedings against the US president heated up.
While Mr McKinley has not been directly involved with Ukraine, he has served as a conduit between Mr Pompeo's office and career staff, according to the Washington Post, which first reported his resignation on Thursday night.
US Secretary of State Mike Pompeo. Source: AFP
House Democrats have issued a subpoena to Mr Pompeo for documents as part of their probe, which centres on a call Trump made to Ukrainian President Volodymyr Zelenskiy in July, which he pressed for an investigation into former US Vice President Joe Biden.
The State Department earlier this week blocked testimony by the US ambassador to the European Union, Gordon Sondland, who was then subpoenaed to appear on 16 October.
Former US ambassador to Ukraine, Marie Yovanovitch, told the impeachment inquiry that Trump ousted her based on "unfounded and false claims" after she had come under attack by Trump personal lawyer Rudy Giuliani.
Mr Pompeo was asked about Mr McKinley's resignation in an interview with Joel Ebert of The Tennessean on Friday and brushed off reports that the adviser was leaving because his boss had failed to protect employees.
"I protect every single State Department employee," Mr Pompeo said. "When the State Department employees are doing things right, when they're behaving in ways that are consistent with the rule of law and working on President Trump's and America's mission, I'll always stand with them; I'll always have their back."
