The state of California has opted not to take part in the Trump administration's effort to send National Guard troops to the country's southern border with Mexico, a Defence Department official confirmed at a briefing Monday.
           
Robert Salesses, a deputy assistant secretary at the department, said California has declined a request to commit more than 200 troops to the effort and said talks with California are ongoing.
           
Earlier this month, President Donald Trump and Defense Secretary James Mattis authorised up to 4,000 National Guard personnel to help the Department of Homeland Security secure the border in four southwestern US states.
           
Currently, 900 National Guard troops have been deployed in Texas, New Mexico and Arizona, officials said.
           
Tyler Houlton, a spokesman for Homeland Security, said California Governor Jerry Brown "has stated publicly that he shares our interest in securing our southern border. DHS and our federal partners are committed to working with the governor to mobilise the California National Guard to assist DHS frontline personnel in our vital missions."

Mr Salesses said the federal government had asked California to provide 237 National Guard troops to two sectors near the Mexican border. "They will not perform those missions," Mr Salesses said.

"We are continuing dialogue, discussion with the California National Guard."
           
He said the tasks sought were primarily operational support,including motor transport maintenance, radio communications,heavy equipment operations, administrative responsibilities andoperating remote surveillance cameras.
           
National Guard troops are not taking part in direct border security, officials said and are not performing law enforcement work.