International donors Tuesday pledged another $2.4 billion in aid to Yemen, bringing the total to $6.4 billion promised this year.

But at a donors' conference in Riyadh, Yemen's Planning and International Cooperation Minister Mohammed al-Saadi told delegates that Yemen will need another $5.4 billion in the short term to aid its transition and overcome economic and security challenges.

In May, international donors led by Saudi Arabia at the “Friends of Yemen” conference pledged $4 billion to help the impoverished state boost the fight against Islamist militants and develop the Yemeni economy.

United States Agency for International Development administrator Rajiv Shah says the United States has pledged $345 million in security, humanitarian and development assistance to Yemen this year.

The pledge is almost double last year's figure.