The U.S. air force has dropped an increased number of bombs on Islamic State targets in Syria and Iraq during the first four months of 2017.
While a total of 9,442 munitions were fired from January to April 2016, that figure climbed to 14,192 in the same period this year, USA Today reported.
Some groups have warned that the increased use of air strikes has resulted in a spike in civilian casualties. The Independent reported that the last month was the "deadliest on record" for the number of Syrian civilians killed by U.S. air strikes.
U.S.-backed ground forces are currently fighting Islamic State militants in Mosul, Iraq's second-largest city, and Raqqa, which has served as ISIS' capital in Syria.
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The increase in bombing "can be attributed to the increased pace of operations in both Iraq and Syria as we target and destroy ISIS," said Lt. Col. Damien Pickart, a spokesman for Air Force Central Command, according to USA Today.
Under President Donald Trump, the number of U.S. ground forces in Syria and Iraq has been increased and authority to launch air strikes has been given to commanders on the ground.
"He delegated authority to the right level to aggressively and in a timely manner move against enemy vulnerabilities," Defense Secretary James Mattis said.
Under former President Barack Obama, decisions to launch air strikes were taken by the top military leadership and often took longer to authorize.
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In Raqqa, U.S.-backed local forces, supported by U.S. special forces advisers, have cut off most exit routes from the city and are preparing a final assault to retake it.
"We carry out the annihilation campaign so we don't simply transplant this problem from one location to another," Mattis added.
Pickart noted that 90 percent of the rockets and bombs dropped were precision-guided.
"The protection of civilians remains a cornerstone of the campaign," he added.
Not everyone agrees with this.
According to the British-based Syrian Observatory for Human Rights, air strikes carried out by the U.S.-led coalition killed 225 civilians between April 23 and May 23, including 36 women and 44 children.
In March, U.S. air strikes in the Syrian cities of Aleppo and Mosul reportedly killed 300 civilians.
The U.S. military acknowledged earlier in May that it was responsible for 352 civilian deaths since the bombings began in September 2014. This figure has been dismissed as far too low by human rights groups.
The SOHR estimates that air strikes have killed 1,481 people, including 319 children, since 2014.