US Secretary of Homeland Security resigns

Washington: The US Secretary of Homeland Security Kirstjen Nielsen has resigned from her post.

US President Donald Trump confirmed Nielsen was leaving on Twitter, writing that "I would like to thank her for her service."

Trump later announced US Customs and Border Protection Commissioner Kevin McAleenan will replace her as Acting Secretary.

"I have confidence that Kevin will do a great job!"

The move comes at a time when Trump has declared a national emergency on the US-Mexico border. He also recently withdrew his nomination of Ron Vitiello to lead the US Immigration and Customs Enforcement (ICE), telling reporters on Friday "we're going in a little different direction...We want to go in a tougher direction."

Nielsen was appointed to the post on 6 December 2017 after her predecessor John Kelly became White House Chief of Staff. She supported the Trump administration's tough stance on illegal immigrants, and oversaw controversial policies including separating immigrant children from their parents for extended periods of time.

In her resignation letter, Nielsen stated that some laws were preventing the DHS from protecting the border.

"I hope that the next Secretary will have the support of Congress and the courts in fixing the laws which have impeded our ability to fully secure America's borders and which have contributed to discord in our nation's discourse. Our country-and the men and women of DHS- deserve to have all the tools and resources they need to execute the mission entrusted to them," she wrote.

"We have implemented historic efforts to defend our borders, combat illegal immigration,obstruct the inflow of drugs, and uphold our laws and values."

Tensions along the US-Mexico border have continued to rise as the Trump administration grapples with an increase in illegal immigration.

According to McAleenan, the number of illegal immigrants caught at the border have skyrocketed.

Highlighting the situation, Trump tweeted, "More apprehensions at the southern border than in many years. Border patrol amazing. Country is FULL! System has been broken for many years. Democrats in Congress must agree to fix loopholes.

"Will close Southern border if necessary," he added. "Mexico must apprehend all illegals and not let them make the long march up to the United States, or we will have no other choice than to Close the Border and/or institute Tariffs. Our Country is FULL!