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Hani Mohammed, Associated Press
A boy and his sisters watch graffiti artists spray on a wall, commemorating the victims who were killed in Saudi-led coalition airstrikes in Sanaa, Yemen, Monday, May 18, 2015. Saudi-led airstrikes targeting Yemen's Shiite rebels resumed early on Monday in the southern port city of Aden after a five-day truce expired amid talks on the war-torn country's future that were boycotted by the rebels.

SANAA, Yemen — The Saudi-led coalition carried out the heaviest airstrikes near the Yemeni capital since the expiration of a five-day truce with Yemen's Shiite rebels, hitting weapons depots in the mountains surrounding Sanaa and shaking several residential areas on Tuesday.

The bombardment began shortly after midnight Monday, with airstrikes targeting rebel-held military depots in the mountains of Fag Atan and Noqom, where missiles, tanks and artillery are kept, the residents said, speaking on condition of anonymity because they feared for their safety.

The Saudi-led coalition has repeatedly struck the two sites since launching the air campaign against the Iranian-backed rebels, known as Houthis, on March 26. But Tuesday's assault was the heaviest since the expiration of a five-day humanitarian truce in place last week, which was repeatedly violated.

Elsewhere in Yemen, missiles hit several Houthi positions in their stronghold in the northern province of Saada and Hajja, as well as gatherings of fighters allied with the Houthis in the western city of Taiz, southern city of Aden, near its airport, and in the eastern province of Marib.

The ground fighting did not stop even during the truce between the Houthis and fighters backing internationally-recognized President Abed-Rabbo Mansour Hadi, now in exile in the Saudi capital of Riyadh.

The Yemeni conflict has killed 1,820 people and wounded 7,330 since March 19, according to UN estimates. The estimates also show that nearly a half million people at least have been displaced in the period since the beginning of the fighting until May 7.

In a show of support to the Saudi-led operation, a gathering of dozens of Yemeni politicians and tribal figures ended in Riyadh on Tuesday with a declaration that called for the formation of special forces to protect Yemen's cities engulfed in the fighting.

The declaration also called for the formation of "safe zones" where "legitimate" Yemeni institutions could operate, though it gave no clear plan on how to set up such special forces or who would be responsible for the safe zones.

When they started on March 26, it was widely believed that the Saudi-led airstrikes would be followed by ground troops. However, almost two months into the campaign, there has been no sign of imminent deployment of ground forces.