The United States has stepped up airstrikes against Yemen, targeting Houthi fighters in the country, the Pentagon said on Monday.

American aircraft carried out 20 attacks over the weekend, according to Pentagon spokesman Navy Captain Jeff Davis.

Davis did not provide details of where and how the air raids were conducted.

“We continue to target AQAP [al-Qaeda in the Arabian Peninsula] in Yemen and this is done in the interests of disrupting this terror organisation that presents a very significant threat to the United States,” he said.

Since U.S. President Donald Trump took office in January, the Pentagon has increased attacks against Houthi fighters in Yemen, with over 70 airstrikes reported just since February 28.

Back in January, an ill-fated U.S. airstrike against Yemen killed dozens of Yemeni civilians including nine children, as well as a U.S. Navy SEAL.

It was the first authorized raid by Trump, who blamed “the generals” after the raid went terribly wrong.

The conflict-ridden Yemen has been under regular U.S. drone strikes, with Washington claiming to be targeting al-Qaeda elements while local sources say the attacks mainly kill civlians.

Saudi Arabia has also been leading a deadly campaign against Yemen since March 2015 in a bid to reinstall Abd Rabbuh Mansur Hadi to presidency.