The US has announced it will keep some of its embassies in north Africa and the Middle East closed for up to a week, due to a possible militant threat.
Twenty-one US embassies and consulates closed on Sunday.
The State Department in Washington said the extended closures were due to the exercise of caution, and not a reaction to a new threat.
US diplomat missions in Algiers, Kabul and Baghdad are among those which will reopen on Monday, Washington said.
A state department global travel alert, issued on Friday, is in force until the end of August.
The department said the potential for an al-Qaeda inspired attack was particularly strong in the Middle East and North Africa.
Embassies closed on Sunday, a working day in the Muslim world, included Amman, Cairo, Riyadh and Dhaka.
The embassy closures and US global travel alert came after the US reportedly intercepted al-Qaeda messages.
It has been suggested that they were between senior figures talking about a plot against an embassy.
Referring to the Middle East, the state department said: “Current information suggests that al-Qaeda and affiliated organizations continue to plan terrorist attacks both in the region and beyond, and that they may focus efforts to conduct attacks in the period between now and the end of August.”
The travel alert called for US citizens to be vigilant, warning of “the potential for terrorists to attack public transportation systems and other tourist infrastructure”.
An unnamed US official has said the threat could be related to the Muslim holy month of Ramadan, which ends this week.
Several European countries, including the UK, have temporarily shut missions in Yemen.