The US wants to keep out drugs, weapons and terrorists
President George Bush has called for a big increase in the budget for the country's immigration service in order to track down people who are staying in the country illegally.
It is his third speech in as many days in which he has outlined measures relating to different aspects of his war on terrorism.
First it was a big hike in military spending. On Thursday he told mayors about more federal help for state and local emergency services. Now President Bush is talking about the need to protect the country's borders.
Illegal immigrants
He said over a quarter of the nearly $40bn homeland defence budget would go on securing the country from attacks by land, sea or air.
He also wants a 29% increase in funding for the immigration service.
His main concern there is the nearly 9 million people living illegally in the United States.
He said that 40% of them have stayed in the country after their temporary visas expired:
"...One of the things we want to make sure of is we find the 40% to make sure they're not part of some al-Qaeda network that wants to hit the United States".
Pre-emptive security
The money will pay for new immigration agents who will work alongside an extra 800 border guards. They are part of a new border initiative now underway with Canada.
This aims to develop a system which identifies potential threats before they reach the border, allowing frequent travellers and goods to flow freely between the two countries.
Mr Bush also said he planned to introduce the biggest ever increase in funding for the coastguard service.
It is all another example of how his number one priority of defending the country is shaping a wide range of policy areas.