U.S. Customs and Border Protection officers will be key players in putting President Donald Trump's revised travel ban into effect on Thursday, affecting visitors from six mostly Muslim countries.
They are the officers dressed in blue who are stationed at airports and border crossings and screen people coming into the U.S. They stamp passports, inspect travel documents, confiscate drugs and other illicit items and make sure belongings and purchases are properly declared.
Customs and Border Protection officers were embroiled in chaos when an earlier version of President Donald Trump's travel ban took effect, forcing them to turn away visa holders who were later allowed in. They will be in the mix again for the new ban affecting visitors from Syria, Sudan, Somalia, Libya, Iran and Yemen.
Here's a look at what they do:
Wat is customs and border protection?
The agency was created as part of the Department of Homeland Security in 2003 after attacks on the World Trade Center and Pentagon. Its largest division - the Office of Field Operations - admits people and goods at 328 airports, land crossings and seaports. They admitted 390 million travelers during the fiscal year that ended Sept. 30, including 119 million at airports.
Much of the work done by the agency is at border crossings along the U.S.-Mexico border.
The busiest point of entry is San Diego's San Ysidro crossing with Tijuana, Mexico, with 31.8 million admissions during the latest 12-month period, an average of 87,000 a day. El Paso, Texas, across from Ciudad Juarez, Mexico, was second-busiest with 28.8 million admissions, followed by San Diego's Otay Mesa crossing (17.8 million), Laredo, Texas (17.7 million), and New York's John F. Kennedy International Airport (15.9 million).
The travel ban will mostly affect airports because that's how visitors from the six countries generally arrive. Aside from JFK, the only airports to crack the top 20 in passenger volume are Miami International (No. 11), Los Angeles International (No. 12) and San Francisco International (No. 20).
How will officiers enforce the tranvel ban?
The Trump administration on Wednesday set new criteria for visa applicants from the six countries and all refugees that require a "close" family or business tie to the United States.
Visas that have already been approved will not be revoked, but instructions issued by the State Department say that new applicants from the six countries must prove a relationship with a parent, spouse, child, adult son or daughter, son-in-law, daughter-in-law or sibling already in the United States to be eligible. The same requirement, with some exceptions, holds for would-be refugees from all nations that are still awaiting approval for admission to the U.S.
Grandparents, grandchildren, aunts, uncles, nieces, nephews, cousins, brothers-in-law and sisters-in-law, fiancees or other extended family members are not considered to be close relationships, according to the guidelines that were issued in a cable sent to all U.S. embassies and consulates late on Wednesday. The new rules take effect at 8 p.m. Eastern Daylight Time on Thursday (0000GMT on Friday), according to the cable, which was obtained by The Associated Press.
The task falls largely to the State Department but Customs and Border Protection officers would get involved if someone from one of the six countries arrived without a visa or there was a reason to question the validity of their documents.
What illegal activity do officers find?
Agents primarily seize drugs and stop people seeking to enter the country illegally.
Drugs - increasingly heroin and methamphetamine - are commonly smuggled into the United States by car from Mexico. People enter the country illegally by hiding in trunks or by using someone else's travel documents.
Officers denied admission 274,821 times at airports, land crossings and seaports during the latest fiscal year, an increase of 8 percent from the same period a year earlier. They seized 257 tons of marijuana, 26.3 tons of cocaine, 18.8 tons of methamphetamine and 2.1 tons of heroin.
An estimated 40 percent of people in the country illegally overstay their visas, and one of the agency's top priorities is to better track them. The absence of a system for people to check out when the leave the country makes that a daunting and expensive endeavor. Homeland Security said in May that nearly 740,000 foreigners overstayed visas during the latest fiscal year, and that was only for those who arrived by plane or ship.
Is it different than border control?
The Border Patrol is another division within the agency. Customs and Border Protection agents wear blue uniforms and patrol ports of entry. Border Patrol agents work areas between and wear green uniforms.
Customs and Border Protection is the nation's largest law enforcement agency, with about 60,000 employees and an annual budget of $13.5 billion. Trump has requested 21 percent spending increase, partly to build a wall on the border with Mexico and hire more Border Patrol agents.
What about the staffing shortage?
The Trump administration said this month that it has 1,400 vacancies for officers at ports of entry. Customs and Border Protection has struggled to fill jobs for years, largely because an unusually high number of applicants fail a pass a polygraph that has been a hiring requirement since 2012. One official recently said 75 percent failed, more than double the average among law enforcement agencies surveyed by The Associated Press.
The House of Representatives passed a bill this month to waive the polygraph requirement for many veterans and some other applicants. Customs and Border Protection recently said it was easing some physical fitness and language requirements in hiring.
The administration has called for expanding the Border Patrol by 5,000 agents but has not proposed any increase in officers at airports, land crossings and seaports.