Us president signs a memo directing troops to the border after days of complaints about weak border policy.

US President Donald Trump has signed a memorandum to deploy the National Guard to the US-Mexico border, citing a “drastic surge of illegal activity”.

Trump signed the proclamation on Wednesday, citing “illegal drugs, dangerous gang activity, and extensive illegal immigrations” as threats to the US.

In addition to the duration, it is also still unclear when and where the troops will be deployed and the costs associated with it.

The move comes a day after the US president said he would rely on the military to guard the border “until we have a wall and proper security”.

In recent days, Trump has published a series of tweets criticising Mexico for its immigration policies and calling on the Congress to pass strict immigration laws, as well as fund his border wall.

Last year, illegal border crossing arrests were at their lowest level since 1971.

The National Guard was sent to the US-Mexico border under the administrations of President George W Bush and Barack Obama as well.

Between July 2010 and September 2011, 1,200 troops were deployed to the southwest border to support border patrol.

President Bush stationed 6,000 National Guard troops in California, Arizona, New Mexico and Texas from June 2006 to July 2008, at a cost of $1.2bn.