US President George W Bush has thanked Colombia's President Alvaro Uribe for his support in the anti-drugs war.
This is the third leg of President Bush's regional trip
Mr Bush was in Colombia's capital, Bogota, for a six-hour visit as part of his five-nation Latin American tour.
Nearby, at least 25 people were arrested as riot police using tear gas clashed with demonstrators protesting against Mr Bush's visit.
Mr Bush praised Mr Uribe's efforts to tackle the country's trade in illegal drugs, much of it destined for the US.
"I appreciate your determination, and I'm proud to call you a personal friend, and to call your country a strategic partner of the United States," Mr Bush told his Colombian counterpart during a news conference.
The visit is overshadowed by a scandal about alleged links between Mr Uribe's allies and right-wing paramilitaries.
Death squad denial
President Uribe denied any ties between members of his government and the death squads at a joint news conference with Mr Bush on Sunday.
Troops have been deployed to boost police presence in Bogota
"If members of the government appear to have links with the paramilitaries, they will be immediately removed from office," he said.
Colombia is one of the largest recipients of US aid to help fight a long-running war against left-wing guerrillas and drug traffickers.
Some US Democrats are questioning a White House request for $3.9bn in new aid over the next seven years as well as the wisdom of a US trade deal with Colombia.
Since 2000, Colombia has received billions of dollars of US funds and military hardware.
But Mr Bush said that he would press for support of further funding for the country's efforts.
"It is going to be very important for our United States Congress to see that determination and I believe that given a fair chance President Uribe can make the case," he said.
Last week, Mr Bush defended the $700m-a-year aid programme and expressed his determination to press for congressional approval of free trade agreements signed with Colombia and Peru.
There have been concerns that guerrillas might try to disrupt the meeting between Mr Bush and Mr Uribe by launching fresh attacks.
Colombian authorities deployed 21,000 troops in addition to 7,000 police who will be responsible for security during Mr Bush's visit.
President Bush has now continued to Guatemala. He had earlier visited Brazil and Uruguay.
Venezuela President Hugo Chavez is on a tour of Latin America at the same time.
On Saturday during a visit to Bolivia, he launched a stinging attack on the US.
Mr Chavez described capitalism as "the road to hell". He underlined the billions of dollars of aid Venezuela is ploughing into Bolivia's economy at a time when the US is reducing its contributions.
In Managua, on Sunday, he accused the US of interfering in the region.
"The North American empire is trying to snuff out the flame of liberty," Mr Chavez said.
President Bush has avoided discussing his rival's regional trip during his own visit to promote trade.
Mr Bush's presence in Latin American states has been met with protests and marches, some of which have turned violent.
About 150 protesters clashed with riot police in Bogota after Mr Bush landed on Sunday, with at least 25 arrested.
About 20 people were arrested in the Uruguayan capital Montevideo on Friday after an estimated 6,000 people took to the streets.