The United States has halted some counterterrorism operations against al-Qaeda militants in Yemen following a takeover of the country by Iran-backed Houthi rebels, US officials said. The collapse of the US-backed government of Yemen on Thursday has left America's counterterrorism campaign "paralysed", two US security officials said, dealing a major setback to Washington's fight against al-Qaeda in the Arabian Peninsula (AQAP), a potent wing of the militant network. Three US officials said the halt in operations included drone strikes, at least temporarily, following the abrupt resignation of the president, prime minister and cabinet amid mounting fears the Arab world's poorest country was veering towards civil war. The US move underscores another setback for US President Barack Obama's Middle East policy and raises doubts about a counter-terrorism strategy that has relied on drone warfare and often shaky foreign partners to avoid sending large US ground forces to battle militant threats far from American shores. Many US personnel work with Yemeni forces at the southern al-Annad airbase, an intelligence post for monitoring the Yemeni affiliate of al-Qaeda, or AQAP, which claimed responsibility for attacks this month in Paris that killed 17 people. Other US officials said the situation on the ground was fluid and described the halt as a temporary measure. "It would mean that AQAP would have a much freer hand in parts of the country," said Lorenzo Vidino, author of Al Qaeda in Europe and an analyst at the Institute for the International Political Studies in Italy. "That means more ability to plan attacks against the US."