Colombian President Gustavo Petro has announced a $4.3bn deal to buy Swedish warplanes at a time when his country is locked in tension with the United States.

Speaking on Friday, Petro confirmed an agreement was reached with Sweden’s Saab aircraft manufacturer to buy 17 Gripen fighter jets, giving the first confirmation of the size and cost of the military acquisition that was initially announced in April.

“This is a deterrent weapon to achieve peace,” Petro said in a post on social media.

The purchase of warplanes comes as Colombia and much of remaining Latin America are on edge due to a US military build-up in the region, and as US forces carry out a campaign of deadly attacks on vessels in the Caribbean and eastern Pacific.

Washington claims – but has provided no evidence – that it has targeted drug smuggling vessels in its 20 confirmed attacks that have killed about 80 people so far in international waters.

Latin American leaders, legal scholars and rights groups have accused the US of carrying out extrajudicial killings of people who should face the courts if suspected of breaking laws related to drug smuggling.

US President Donald Trump has also accused both Petro and his Venezuelan counterpart, Nicolas Maduro, of being involved in the regional drug trade, a claim that both leaders have strenuously denied.

Petro said the new warplanes will be used to dissuade “aggression against Colombia, wherever it may come from”.

“In a world that is geopolitically messy,” he said, such aggression “can come from anywhere”.

The Colombian leader has for weeks traded insults with Donald Trump and said the ultimate goal of the US deployment in the region is to seize Venezuela’s oil wealth and destabilise Latin America.

Trump has long accused Venezuela’s Maduro of trafficking drugs and more recently branded Petro “an illegal drug leader” because of Colombia’s high level of cocaine production. Trump has also withdrawn US financial aid from Colombia and taken it off its list of countries seen as allies in fighting drug trafficking internationally.

Amid the war of words rumbling on between Washington and Bogota, Petro said last week that Colombia would suspend intelligence sharing with the US on combating drug trafficking, but officials in his government quickly rolled back that threat.

The AFP news agency reports that US and French firms had also tried to sell warplanes to Colombia, but, in the end, Bogota went with Sweden’s Saab.

Swedish Defence Minister Pal Jonson said Colombia was joining Sweden, Brazil and Thailand in choosing the Gripen fighter jet, and defence relations between Bogota and Stockholm would “deepen significantly” as a result.