CHICAGO, IL - MAY 20: U.S. President Barack Obama (R) and NATO Secretary General Anders Fogh Rasmussen (L) greet Spainish Prime Minister Mariano Rajoy Brey as they arrive at the NATO summit on May 20, 2012 at McCormick Place in Chicago, Illinois. As sixty heads of state converge for the two day summit that will address the situation in Afghanistan among other global defense issues, thousands of demonstrators have taken the streets to protest. (Photo by John Gress/Getty Images)2012 Getty Images
The meeting Monday between Spanish Prime Minister Mariano Rajoy and U.S. President Barack Obama comes at a time of close cooperation between the two countries, which have a relationship stretching back 229 years.
Although bilateral relations have gone through some difficult periods, most recently in 2004 when former Prime Minister Jose Luis Rodriguez Zapatero's government withdrew Spanish troops from Iraq, nowadays they are close and cordial, Spanish officials said.
A promising future is opening up in the relationship, according to the Spanish Foreign Ministry, in which the growing Hispanic element in the United States is having a more and more pronounced influence.
Some differences persist - with regard to recognition of the unilateral declaration of independence by Kosovo, for instance - and there are still pending questions, including the removal of contaminated soil in Palomares, Spain, where in 1966 four nuclear bombs landed after the high-altitude collision of two U.S. military aircraft.
The non-nuclear explosives in two of the weapons detonated upon impact with the ground, resulting in the contamination of a 2-square-kilometer (490-acre) area by plutonium.
Other more current questions could be dealt with during the meeting between Rajoy and Obama, including the alleged massive electronic espionage conducted by the National Security Agency, or NSA, on foreign leaders and millions of common citizens all over the world.
The investigation into the 2003 death in Iraq of Spanish journalist Jose Couso is another unresolved issue.
Over the course of more than two centuries of diplomatic relations since 1785 there have been noteworthy events, such as the U.S. acquisition of Florida from Spain and the Spanish-American War in 1898, which ended with Washington controlling Spain's former colonies of Puerto Rico, Guam and The Philippines and the withdrawal of Spain from Cuba.
After diplomatic relations were interrupted between 1946 and 1951 due to the Franco dictatorship's policy of nominal - but Axis-leaning - neutrality in World War II, in 1953 the Madrid Accords were signed whereby Spain received economic, technical and military aid in exchange for allowing the United States to build and use military bases on Spanish territory.
In 1959, President Dwight Eisenhower made a state visit to Spain, indicating U.S. support for the regime of Francisco Franco.
After the dictator's death in 1975, bilateral relations entered a new phase marked by U.S. support for democracy.
Spain provided logistical support to Washington during the 1990-1991 Gulf War and in 2003 Madrid was a key nation supporting the Iraq War.
After a period of cool relations after the 2004 ascension to power of socialist Rodriguez Zapatero, who opposed the war, relations moved onto a more normal footing with Obama's presidency and Spanish support for the U.S. strategy in Afghanistan.