By James Painter
As Colombia's bitter armed conflict drags on well into its fifth decade, most observers agree that the left-wing rebels from the Farc (Revolutionary Armed Forces of Colombia) continue to use border areas in neighbouring countries for rest and recreation.
Colombia's neighbours are keen to contain the conflict
There have been no major incidents of soldiers from Venezuela, Ecuador, Peru or Brazil being dragged into the fighting.
The policy of Colombia's neighbours has been to try to avoid any direct involvement in the war or engagement with the Farc, and to contain any possible spill-over.
However, on the diplomatic front, there are regular spats between Colombia and two of its neighbours, Ecuador and Venezuela, over issues related to the Farc.
And the conflict continues to cause a major humanitarian headache, both inside and outside the country. Millions of Colombians have been forced to flee from their homes.
VENEZUELA - CLOSE BUT TENSE TIES:
Bilateral relations have long been close but tense, due in part to disputes over the delineation of their border and also as a result of Colombia's conflict spilling over into Venezuela.
The two countries share a 2,200km (1,400-mile) border. Colombia has often claimed that the left-wing President Hugo Chavez of Venezuela harbours Farc members and turns a blind eye to guerrilla camps on Venezuelan soil.
Mr Chavez says he is neutral in the conflict, although he is not unsympathetic to the Farc and enjoys amicable relations with them.
Much divides but also unites Colombia and Venezuela
In January 2008 he said the Farc should been seen as an insurgent force not a terrorist group, which is how the Colombian government as well as the US and the EU designate them.
Right-wing President Alvaro Uribe of Colombia wants much greater co-operation in the fight against the Farc.
But President Chavez, who is fighting his own war of words with Washington, is very reluctant to co-ordinate army operations with Colombia, particularly when Mr Uribe is such a strong ally of US President George W Bush.
In the last three years, relations have gone through periods of greater and lesser tension. In early 2005 they hit a low point after the Uribe government admitted it had paid bounty hunters to capture a leading Farc member (Rodrigo Granda) and take him to Colombian territory.
Mr Chavez accused Colombia of violating his country's sovereignty and temporarily suspended bilateral trade agreements.
November 2007 was another very low point after Mr Chavez failed in a mediation effort to secure the release of several Colombian hostages being held by the Farc.
Mr Uribe accused him of talking directly to the head of the Colombian armed forces against his wishes and suspended his mediation mission. Mr Chavez declared that relations with Colombia had been "frozen" and later broken off.
However, the end of the year saw the release of two of the hostages with Mr Chavez's involvement.
There have also been periods of more mutual respect. Both leaders share a populist streak even though they are at opposite ends of the political spectrum.
And the two countries share strong economic ties pulling them together. Each country is the other's largest trading partner after the United States.
Trade is worth around $6bn (£3bn) and Colombia exports a whole range of goods from manufactured products to food staples such as milk. There is also a $200m cross-border gas pipeline among other major joint projects, by which Colombia exports gas to Venezuela.
ECUADOR - ASSERTING NEUTRALITY:
The impact of the conflict has been felt acutely in Ecuador. Relations between the two countries have been seriously harmed and are often delicate.
In the two Colombian border departments of Narino and Putumayo, there is reported to be a strong presence of the Farc, and to a lesser extent of right-wing paramilitary groups and drug-traffickers.
Ties between Mr Uribe and Mr Correa are now more cordial
Ecuador is a major destination for Colombians fleeing the armed conflict, and is home to about 250,000 undocumented Colombian refugees according to the UN refugee agency, the UNHCR.
Ecuador wants a greater Colombian military presence along the border and compensation for receiving the displaced population.
The Colombian government, for its part, often accuses the Ecuadorean military of allowing the Farc to use Ecuadorean territory as a base for attacks.
The Ecuadoreans say the Colombian military at times crosses over into Ecuador in pursuit of the Farc.
They are reluctant to get involved in joint operations as it could involve the military in protracted operations and provoke retaliatory action from the Farc against oil installations or pipelines. Engaging militarily with the Farc would also be unpopular with the electorate.
Another area of dispute that surfaces at regular intervals is over the Colombian government's aerial fumigation of suspected coca-growing areas along the joint border.
Ecuador maintains that the herbicide used in the fumigation drifts across the border and infects humans and cattle. It also adds to the forced migration of Colombians into Ecuador.
But Colombia maintains the fumigations are necessary to clamp down on coca production, which they say funds operations by the Farc.
However, in January 2007 the two governments reached an agreement to coordinate better on fumigations. They are currently suspended in an area within 10km (six miles) of the border.
Relations between Mr Uribe and the left-wing president of Ecuador, Rafael Correa, got off to a rocky start but are more cordial now.
In April 2007, the Correa government proposed its own "Plan Ecuador" to promote social investment in the border area for both Colombians and Ecuadoreans as an alternative to the US-backed Plan Colombia.
BRAZIL - REGIONAL SUPERPOWER:
Relations between Brazil and Colombia have improved in the last few years despite ongoing concerns from President Luiz Inacio Lula da Silva's government about drug trafficking activities in the border areas and the possibility of the conflict spilling over into Brazil.
The problem of cocaine trafficking remains but there have been some improvements in the bilateral efforts to curb it.
That includes more effective information sharing that helped the Brazilian police to arrest Juan Carlos Ramirez Abadia, one of the most important Colombian drug barons, in August 2007.
Brasilia seems less concerned than previously about guerrillas from Farc using its territory for military training and other activities. This may reflect the view that the Colombian government under President Uribe has been more effective in controlling the border area and fighting the rebels.
PERU, BOLIVIA AND COCA:
Peru and Bolivia are the world's next largest producers of coca, the raw material of cocaine, after Colombia.
Cracking down on coca production in one place can boost it in another
Coca-growers in the two countries are often accused of having close links with the Farc, although this has never been proved.
More worrying for the authorities in the two countries is that US pressure on Colombia to reduce its coca production can cause a "balloon effect".
Some analysts say this was evident in the figures released in June 2007 by the UN Office on Drugs and Crime. They show coca cultivation fell in 2006 by 9% (to about 78,000 hectares) in Colombia, but increased in Peru and Bolivia by 7% and 8% respectively.
REFUGEES AND DISPLACED PEOPLE
The UNHCR says that an estimated half a million Colombians have fled their country due to the violence or the violation of their human rights.
Of these, in January 2008 more than 17,000 had applied for asylum in neighbouring countries.
Most of them have fled to Ecuador (250,000) and Venezuela (200,000), but they are also to be found in Panama (13,500), Costa Rica (6,000) and Brazil (17,000). Several thousand, many from indigenous groups, live like refugees in the remote Amazon region of Brazil.
The situation along the border with Ecuador is particularly unstable.
In August 2007, 1,700 Colombians, most of them women and children, fled to Ecuador to escape a flare-up in violence. President Uribe blamed the Farc for pressurizing the local population to resist plans to cut down coca plantations manually rather then by aerial fumigation.
Estimates vary as to the number of internally displaced Colombians as a result of the conflict, but a widely quoted figure is two million, which is the second highest number in the world after Sudan.
The UNHCR says the situation is particularly precarious for internally displaced families headed by single women, adolescents vulnerable to forced recruitment into militias, and older people.