Saudi Arabia is facing intense pressure from the United Nations and humanitarian non-governmental organizations after a damning UN report was released over the weekend.
The Saudis heavily bombarded Yemen from Friday into Saturday, in an intense attack that the UN called a "breach of international humanitarian law."
The Saudis attacks against Houthi rebels in Yemen - 130 airstrikes in a 24-hour period - targeted schools and hospitals, as well as densely populated civilian areas.
The Saudis gave very little prior warning of the attacks on populated areas, which is a requirement under the Geneva Convention, which governs international rules of war.
Saudi spokesman Brig. Gen. Ahmed Asiri claimed in a statement that the hospitals and schools functioned as weapons storage sites and was "targeting headquarters of the Houthi leaders."
The attacks took place on the cities of Sadaa, Maran, Albiqaa and the border area between Saudi Arabia and Yemen.
That rationalization for Friday and Saturday airstrikes was rejected by Johannes Van Der Klaauw, the U.N. humanitarian coordinator for Yemen.
"The indiscriminate bombing of populated areas, with or without prior warning, is in contravention of international humanitarian law," Van Der Klaauw said in a statement.
The UN was especially concerned about the attacks on Saada, "where scores of civilians were reportedly killed and thousands were forced to flee their homes after the coalition declared the entire governorate a military target."
The Saudis want to restore the Yemeni government, a key U.S. ally in the fight against al Qaeda, which lost the capital city earlier this year to rebel forces .
The Saudis see the Iranian-backed Houthis as a threat, analysts say, and are looking to take concrete measures to prevent the spread of Iranian influence within the region.
The conflict has seen more than 1,400 killed since mid-March and nearly 6,000 injured, Van Der Klaauw said.
Doctors Without Borders, a prominent international aid organizations present in Saada, verified the heavy bombing and also condemned it.
"The bombing of civilian targets, with or without warning, is a serious violation of international humanitarian law," said Llanos Ortiz, MSF medical coordinator in Yemen. "It is even more serious to target a whole province."
It is impossible for an entire population to leave within a few hours, Ortiz said. Most Saada residents lack vehicles to flee or access to phone or other communication networks, he added.