Even before taking office, US President Donald Trump's relationship with NATO has been a tumultuous one, to say the least. He has disparaged the trans-Atlantic alliance, once describing it as "obsolete" and a relic of the Cold War. Here are Trump's most memorable quotes about the military alliance, even if they are at times false.

While on the campaign trail in 2016, Trump made clear that he saw NATO as a relic of the Cold War. "You know, we're dealing with NATO from the days of the Soviet Union, which no longer exists. We need to either transition into terror or we need something else." But his remarks didn't account for how the alliance backed the US well after the collapse of the Soviet Union, especially in Afghanistan.

Trump has made defense spending his main talking point on NATO. But he has falsely accused member states of owing money to Washington, saying: "Germany owes vast sums of money to NATO, and the United States must be paid more for the powerful, and very expensive, defense it provides to Germany." The problem is NATO doesn't work like that. No money is owed to the alliance for defense or otherwise.

Days before his inauguration, Trump caught NATO members off guard when he claimed the alliance was "obsolete" and threatened to withdraw support. "I said a long time ago that NATO had problems: Number one, it was obsolete, because it was designed many, many years ago." Months later, he retracted his statement, citing changes within the alliance. "Now they fight terrorism," he said.

Trump had tended to lump trade between US allies with how much Washington spends on defense. "We are spending a fortune on military in order to lose $800 billion (in trade losses). That doesn't sound very smart to me," Trump said. The problem is that while NATO members have agreed to spend 2 percent of their GDP on defense, the alliance has nothing to do with international trade.

During a 2018 rally in Montana, Trump hit out at European allies, saying: "They want (us) to protect against Russia, and yet they pay billions of dollars to Russia, and we're the schmucks paying for the whole thing." Trump was referring to Russia as Europe's primary source for oil and natural gas, but he created a false dichotomy between energy reliance and NATO's defense spending goal.

In an interview with Fox News, Trump was asked why the US should jump to the defense of NATO ally Montenegro if it was attacked. The president said he asked himself the same question, a remark that appeared to undermine the alliance's collective defense clause. Trump went on to describe Montenegrins as "very strong" and "very aggressive," and that that aggression risked starting World War III.

Many different animals are used for highly specialized tasks. Dogs are often used by law enforcement and customs officers, and they're also deployed to detect drugs, explosives, and even data carriers. US General McKenzie has said military dogs "help protect US troops, save the lives of civilians, keep combatants and non-combatants apart, and immobilize hostile individuals."

Security agencies also enlist the help of other animals, however. Dutch police, for example, use eagles to fight enemy drones. Should drones get too close to nuclear power plants or such key sites, the birds can bring them down. Dutch authorities train the eagles to treat drones as potentially pray. But there are other heroic birds, too — like canaries ...

So, what special ability can canaries offer? Can they hunt down terrorists, sniff out explosives, or bring down dangerous drones? None of the above. But they have been deployed along the border between North and South Korea to detect poisonous gas.

South Korea was concerned North Korea could attack it with toxic gas, so it set up cages with canaries along the border. If the birds would fall of their perch and die, South Koreans would know it was time to don the gas masks. Why? Because canaries are so small that they are much more susceptible to tiny amounts of gas.

Laika, a small Russian dog, was the first ever animal to be launched into space. It happened on November 3, 1957, and was intended to show off the Soviet Union's spaceflight prowess. Laika, however, paid with her life. It is believed she died from stress and overheating. She was not the first animal with such a special mission, however.

Pigeons used to be deployed to send messages, which were written on pieces of paper that they carried. In World War I, they were also used to take photographs of enemy positions. Unfortunately, the cameras used at the time could only take one or two photographs. Later, they were reportedly able to snap up to 12.

Like dogs, rats also have a keen sense of smell, and because they are so much lighter, they are used in some parts of the world to detect land mines; there is a much lower risk that they might accidentally set off an unexploded land mine. But what do you do about naval mines? What kind of animals can hep detect them?

There is an animal that is perfect for finding underwater mines: the dolphin. This one answers to the name K-Dog and shows off a camera mounted on its pectoral fin. It is employed by the US Navy. During the Cold War, both the US and the Soviet Union used dolphins in their naval marine mammal programs. Russia claims it has phased out the program; the US has not.

In addition to dolphins, the US Navy also uses seals to detect water mines, as seen here in a training exercise in Bahrain. Beyond mines, seals and dolphins can also detect divers and protect ships and ports. It has been rumored that dolphins can also be used for attacks, for instance, by attaching mines to enemy vessels.

Finally, we turn to a military and police veteran: the horse. Horses have been used for military and policing purposes for millennia. In the Middle Ages they carried knights; today they carry police officers — as above, working security at a soccer match in London. What makes them such good animals for the force? Well, they work like a horse, of course.