LISBON, Feb. 12 (Xinhua) -- U.S. Ambassador to Portugal George Glass said on Tuesday that U.S. airbase in Lajes of the Azores archipelago of Portugal is "fundamental" for security in the Atlantic and the size of its missions there has come to increase.

Glass said that he was confident of the continuity of the U.S. airbase in Lajes, which in 2015 suffered a military reduction that led to the elimination of hundreds of jobs, including the termination by mutual agreement of about 400 Portuguese officials.

"It is increasing in the size of its missions and has been a tremendous success in the last 18 months since I arrived," Glass said.

He was speaking to reporters at the end of a visit to the detachment of about 300 U.S. military personnel in Monte Real Air Base in Leiria, some 170 km north of the capital city of Lisbon.

Asked about the process of decontamination of soils and aquifers by the U.S. Air Force on Terceira Island, where Lajes air base is located, Glass stressed that the U.S. is working hard to finish the work.

"We have already completed six sites, we will conclude another two and now there is a handfull," he said, noting that the regional government of the Azores should "make an announcement soon" on this matter.

The contamination of soils and aquifers in Praia da Vitoria on Terceira Island, caused by the U.S. Air Force at the Lajes base, was identified in 2005 by the Americans themselves and confirmed in 2009 by the National Laboratory of Civil Engineering (LNEC), which has monitored the decontamination process since 2012, according to Portuguese Lusa News Agency.

In 2015, the United States announced that it would gradually wind down its operations in Lajes. The economic implications of the decision are of grave concern to Portugal.

The situation seemed to have changed when President Donald Trump took office. The Trump administration has proposed extra spending on defense and vowed not to withdraw from Lajes.