DERA ISMAIL KHAN, Pakistan – Three suspected U.S. missile strikes in less than 12 hours hit militant targets in northwestern Pakistan on Wednesday, officials said, an unusually intense barrage that follows four other such attacks in the last week. At least 14 suspected militants were killed.

The strikes were in North Waziristan, a lawless region home to insurgents battling foreign troops just across the border in Afghanistan, al-Qaida leaders plotting attacks in the West and extremists behind bombings in Pakistan.

The militants have stepped up their own attacks in Pakistan in recent days, just as the army focuses on helping millions of victims from the worst floods in the country’s history.

Four big bombs have killed at least 135 people in less than a week.